— The Fishroom Library Archives —
Articles on Breeding Killifish, Incubating and
Hatching Eggs, and Raising Fry (2001 – 2005)
An archived collection of articles, tips, and information about tropical fishkeeping in general, and killi-keeping in particular, from past issues of the G.C.K.A. Newsletter. To read an article, please click on the title (in blue).
All material is copyright © G.C.K.A. or the authors, unless otherwise noted. Reproduction is permitted for non-commercial purposes only (i.e., club bulletins). We do request that you provide source credit, and send us a copy of the publication in which the article appears. Please forward to G.C.K.A., c/o Recktenwalt, 4337 Ridgepath Drive, Dayton, OH 45424.
Amazing things, those killie eggs – Water Incubating Annual Eggs
Asellus as Egg Custodians? Some “pests” are handy to have around.
A Tip for Fry Tanks – from George Morris.
Bellysliders in annual killifish – some observations
Bellysliders in Fry
Black Sand for Spawning – one killiekeeper’s experience.
Blue Gularis … Always a Surprise – A few observations and techniques.
Breeding Peat Divers – an alternate suggestion for spawning media.
A Technique for Catching Fry – a suggestion.
A Couple of Experiences with Coconut Coir – as a spawning medium for annuals.
Condos for Your Killies? – a “high-rise” for eggs and fry.
Dangers to Your Killie Eggs – what to watch out for.
Dominant Males Get All the Girls? Not Always! – those “sneaky” males!
Egg Color – what influences it.
Finding Eggs in Peat – by Wright Huntley.
Floating that mop … flotation devices for plant spawners
Fry the Easy Way – a “no fuss” method for raising plant-spawners.
Harvesting … Gravel? A technique for recovering those “lost” eggs.
Hatching Annuals – A Method to Try
Hatching Out Blue Gularis – one breeder’s experience.
Hatch Water – a good topic for discussion.
How Many Fry in a Growout Tank? – Some things to consider.
Incubating Eggs … Several Methods (advice from the experts)
Incubating Eggs on Peat… Several Methods – more advice from the experts.|
A Quick Course in Inheritance – basic genetics, applied.
Java Moss – Mops? – one aquarist’s technique.
Light Change Triggers Spawning? – some observations on spawning behavior.
More on Eggs – notes from some of the “experts.”
A technique with … Nothos – one breeder’s way to success.
Oak Leaf Mold – a different spawning medium
“Peatless” Bottom Spawning – alternative spawning media.
Peat Moss and Annual Killies – words of wisdom from Roger Brousseau.
Pre-Wetting Peat Before Hatching – a technique to try when those eggs won’t hatch.
Problems Catching Fry? – a couple of suggestions.
Raising Fry … several views – how some breeders do it.
Sex Determination in Fish – how is it influenced, and when does it happen?
Some Views on … Skewed Sex Ratios in Killifish – more on this topic.
Another View on Skewed Sex Ratios.
Some Observations on Using Peat
Spawning Media for Annuals – some potential substitutes for peat moss.
Spawning Mops – some observations.
Spawning Preferences – It’s an individual thing.
Storing and Hatching Eggs … Alternative Methods – some ideas to try.
Storing and Hatching Eggs … Storage on Peat – a few techniqiues.
Techniques to Try for Annuals – breeders share some tips for success.
Those !# Sex Ratios! – a few observations.
A Trick for Fry Boxes – to get those precious fry off to a better start.
Two Hatch Water Recipes
Water Flow and Egg Production – some species need flowing water, others don’t.
Water Incubating SJO (Blue Gularis)
Weather Changes, Barometric Pressure, and Breeding Fish – is there a correlation between changing weather patterns and egg production?
Amazing things, those killie eggs …Water Incubating Annual Eggs
Most species of killifish lay eggs that incubate for a few weeks in water. There are a number of species whose eggs can stay "dry" for months, safely buried in the substrate, and there are a few species whose eggs can be handled (with some variations) either way.
Most of us are familiar with the basics of spawning and incubating both the water and peat incubating killies. For the former, spawn the fish, then keep the eggs in clean water until hatching. For the latter, spawn the fish in peat (or another suitable medium), then store the eggs in slightly damp peat for the recommended time before wetting.
However, eggs from plant spawners (which lay only a few eggs at a time) can be successfully stored and incubated on damp peat. Using this method, newly laid eggs are collected over the period of a week, then carefully placed on the surface of damp peat in a suitable container. This storage method will delay development for up to several weeks, allowing a larger total hatch of fry that are all the same size.
Likewise, eggs from some of the "annual" killifish, which traditionally require long incubation periods in peat, can be hatched in water much more quickly.
This variability is part of the natural flexibility of species, which allows them to take advantage of whatever natural conditions may occur. Annual killifish are genetically "programmed" to produce eggs that hatch out at various times. This is why "rewetting" peat often produces fry over a period of weeks.
It has long been known that higher temperatures and wet peat reduce incubation times. If kept in wet peat, eggs often remain anaerobic and only begin to develop when oxygen is more readily available, i.e., the peat is drier. If kept in water, oxygen is readily available, so development progresses.
The technique of incubating annual eggs in water is hardly new. Jerry Shapiro did it and reported on it in The Journal of the American Killifish Association (JAKA), 1989, 22(1):3-22. His method was loosely based on a technique used by Dr. Jules Markofsky of Roosevelt Hospital, New York, who used Nothobranchius guentheri as a laboratory subject and water hatched many without any dry incubation whatever.
"I [have] used this technique on virtually all members of the N. palmqvisti group with excellent results," says Charles Nunziata. "Also N. rachovii, N. melanospilus and a few others. The technique allows fish to be produced in a matter of weeks rather than months."
"Fast egg development in Nothos is nothing new," agrees Dr. Roger Brousseau. "I regularly hatch out Notho eggs in three weeks. I generally even hatch out South American annuals at this short incubation time."
"The critical factor," points out Brian Watters, "is that the eggs must be exposed to well-oxygenated conditions from the time they are laid." If they aren’t, they’ll be locked in early diapause and no amount of oxygen will get them to develop, for a few months at least.
An article by Allen Johnson in the Nov./Dec. 1993 issue of JAKA, "A New Method for Substrate Spawning Annual Killifish" describes a variation on this concept. The author set up the spawning medium in an operating box filter, without the top cover. Oxygen was thus available to the eggs at all times. Fry begin to appear after 3-4 weeks.— G.C.K.A. Newsletter, December 2002 Return to top of page
Asellus as Egg Custodians?
Asellus, the common freshwater isopod, has been reported as an effective "egg custodian" in aquaria. Personal observation and various trials have indicated that Asellus actually attack fungus, while leaving healthy eggs alone.
"Last year I visited Marc Bogarts and ... Henri DeBruyn," reports Dave Koran. "They showed me the use of some of our ‘pests’ to aid in the fishroom." Mark had active Asellus cultures in his breeding tanks. They scavenged the fish mops, feeding on the fungused or bad eggs, and didn’t seem to make a dent in egg production.
Henri had introduced copepods (ostropods?) into his fry containers. The fry didn’t eat them, but the copepods scavenged the uneaten brine shrimp and microworms, keeping the containers cleaner.
Perhaps we need to rethink our beliefs on some of the aquatic species we consider "pests."– G.C.K.A. Newsletter, November 2005 Return to top of page
A Tip for Fry Tanks
"I like to add snails to the 2.5 gal. tanks that I hatch eggs in," says George Morris, "to keep it clean for the few weeks the fish stay in there. But I don’t want snails there when I hatch the next bag of peat."
How to accomplish this? "I put the tank in the microwave for a minute or so on high. No harsh chemicals, no snail eggs, and no ‘ghost eggs’."
The method works for him!— G.C.K.A. Newsletter, August 2003 Return to top of page
Bellysliders in annual killifish … some observations
Despite the aquarist’s best intentions and greatest care, bellysliders still happen in batches of fry, particularly among the annual killifishes. There are no proven causes for the problem, but anecdotal evidence seems to point to several possibilities.
"I have seen a couple of reasons why peat incubated South American annuals may have more belly sliders," says Lee Harper. "None of these are proven, just anecdotal observations."
1. Eggs remained too long in the final stages of diapause before immersion (weakened fry)
2. Eggs were incubated too short a time before immersion (undeveloped fry). This usually results in no hatch, but fry hatch out upon a later rewetting.
3. Peat is too wet (low oxygen levels)
4. Water is too deep when wetting eggs (1/2 inch or less is preferred)
5. The incubation temperatures are too high (70-75ºF is usually ideal).
Some belly sliders may occur under "normal" conditions, since incubating eggs develop at different rates. Whether fry develop at different rates naturally, or due to differing conditions within the spawning medium is unknown.
In the long run, different rates of development in annual eggs works well for species survival, since there is a greater likelihood that when the rains arrive at least some eggs will be ready to hatch. Additionally, there is usually a reserve of resting eggs still in the pond mud if the water dries up before this season’s hatch of fish can mature and reproduce.
"The same thing happens in hobbyist’s conditions," Lee points out, "so that a normal wetting will produce many fry, but a subsequent re-wetting ... can produce additional fry."— G.C.K.A. Newsletter, August 2002 Return to top of page
Bellysliders in Fry
You've done everything right with your annual spawners, as far as you are able.
You've successfully spawned the fish. You've incubated the eggs according to your own experience and the best recommendations you can find. Now the eggs have hatched, and a proportionately high number of the resulting fry simply lie on the bottom, unable to properly swim.
You have a batch of bellysliders.
Why?
No one really knows why bellysliders occur in killifish fry, but they do, and the phenomenon happens not only in killifish. It is a problem of major concern among many species of importance to commercial aquaculture.
In explanation, a number of possible theories have been suggested, among them the dissolved oxygen content of the water, the degree of surface tension, possible premature hatching, and whether or not the fry "gulp" air at the surface to fill their swim bladders.
A number of experiments have been conducted in attempts to define and solve the problem, both by amateurs and by members of the scientific community. So far, no real explanation has been found. However, some interested information has resulted from this observation, research, and experimentation.The Initial Breath
Evidence indicates that there is a critical time period after the fry breaks free from the egg during which it must initially fill its swim bladder, or the fish will never be able to do so, or to swim normally. In Jordanella floridae the fry seem to be “preset” to swim almost vertically upon hatching. They then tend to sink quickly, and only afterward assume a more normal posture and often begin to feed just beneath the surface.
Among the fry of annual fishes there appears to be a marked tendency to swim upward, with a sudden thrashing dash to the surface. This has been interpreted, perhaps incorrectly, as the drive to “get that first gulp of air.” However, numerous experiments have shown that in most fry the swim bladder develops normally, even when fry are denied direct access to the water’s surface. Thus this “drive” may simply be a natural instinct to get out of the bottom mud with its reduced oxygen levels and into cleaner, more oxygen rich water.
Filling the Swim Bladder
Fish typically fill their swim bladders through a physiological process whereby gas is transferred from the bloodstream to the swim bladder. In some types of fish newly hatched fry have an opening between the foregut and the swim bladder, a connection that soon closes as the fry develop. Almost all fish with swim bladders also have a gas gland, which exchanges gases between the blood and the lumen of the bladder. In some fish this doesn’t become functional until several days after hatching.
“Physotomous fish,” points out Barry Cooper, “have a direct connection between the gas bladder and the esophagus. They potentially can take air directly into the gas bladder by ‘gulping’ at the surface. Physoclistous fish have no such connection.” In all fish there is a complex vascular rete immediately adjacent to the gas bladder wall. Gases, primarily oxygen and nitrogen, are exchanged between the gas bladder and the blood, allowing for constant adjustment of gas levels in the bladder.
Some species of fish have been observed to actually gulp small air bubbles at the surface, with the air then absorbed through the intestine. It is possible that for some fish inflating the swim bladder is dependant on their ability to gulp a few air bubbles at the surface, but for small fish fry the effort to reach the surface can be extreme. Adding aeration or peat to the water helps to reduce the surface tension, making the task easier. It may also be that fry raised in shallow water experience more of a developmental stimulus from the change sin pressure associated with shallow water.
Premature Hatching
Another possible explanation for the occurrence of bellysliders is that the fry are hatching either too early, or too late. If the fry are not completely developed at hatching, they may lack essential physiological development to cope with the stress or life in the unprotected aquatic environment, or may be physically incapable due to developmental lack, to fill their swim bladders. If they hatch too late, they may have already exhausted their energy stores and may be unable to properly recover and swim.
In some cases the fry hatch from the egg, but lay on the bottom for a day or two until they absorb the yolk sack, after which they begin to swim in normal fashion.
Various Other Factors.
There is some anecdotal evidence that the depth of the hatching water for annual killifishes influences the number of resulting bellysliders. Lee Harper says that he has had conversations with several Notho keepers who agree that a half inch maximum depth seems to work best.
Another theory suggests that if the storage peat is too wet, you'll get a lot of bellysliders. "I don't think that is a factor in bellysliders," says Dr. Dan Nielsen, "nor are incubation temperatures." These may have an effect on hatchability, however. He feels that the tendency to bellyslider may be inherited.
"I basically do things the same way ever time, yet some hatches of some strains [of annuals] will have a high rate of bellysliders and others almost none… I think that fry that hatch and can't get off the bottom,, the almost mature fish that suddenly are found on the bottom of the tank in that peculiar twisted position, and the older fish that show the same signs, is all the same disease."— G.C.K.A. Newsletter, February-March 2003 Return to top of page
Black Sand for Spawning
Those fishkeepers who breed the substrate spawning species (Cynolebias, Nothobranchius, etc.) are often interested in trying new spawning materials in place of the traditional peat moss, which can be messy, hard to handle, and can change the water parameters.
For one killikeeper who was having trouble with Nothos, peat was much of the problem What to do? Searching at a local fish store, he discovered Estees’ marine sand. Unlike many sands, which are highly abrasive, this product is quite suitable for use with bottom spawning fish. It is a glossy, fine gravel about the size of large buckshot or pharmaceutical grade charcoal. It comes pre-washed and ready to use, and is available in several colors, including black.
He bought some of this black sand and started spawning his fish over it. The eggs hatched in record numbers, but when he told fellow breeders about his success, they told him he was using the wrong kind of sand.
By then, of course, it was too late. He already had plenty of sand, hundreds of eggs, and tanks full of Nothos. The method worked, so why change?
To use the black sand for spawning, wash it well, then fill a dessert or similar dish half full. Let the fish spawn in it. To harvest the eggs, remove the dish from the spawning tank, then swirl the water and sand with your finger. The eggs will float out and gather at the center of the dish. Siphon them out, then store in peat the usual way.— G.C.K.A. Newsletter, October 2003 Return to top of page
Blue Gularis … Always a Surprise
Killifish can surprise us, and often do.
Breeders occasionally encounter the problem of eggs that do not appear to be developing. They don’t go bad, they simply refuse to develop.
Bob Schwiegerath reports that he has encountered this problem in the eggs of Blue Gularis (Aphyosemion sjoestedti).
"I have bred Blue Gularis for many years," he says. "I water incubate their eggs, and at 75ºF they are usually fully developed and ready to be force hatched at about 5 weeks.
"Occasionally I will get a batch of eggs which don’t begin to develop at all for several months. The urge is to just garbage them, assuming they are infertile, yet they remain clear."
One evening, he checked two of his egg trays and found that suddenly about half of the eggs (collected June 28, 2001) were fully developed and ready to hatch. After the first four weeks of incubation, he had checked the eggs weekly and had found no development.
He set up a small tank with some aquarium gravel and Java Moss. Using the same water as he had used in the tank, he gave the eggs a 100% water change, and placed them in an open 15ml test tube. Checking the test tube an hour later, he found that virtually all the eggs had hatched.— GCKA Newsletter, July 2003 Return to top of page
Breeding Peat Divers – Another technique to try
Although the traditional spawning medium for annual killifish is peat moss, it is not the only suitable spawning medium. However, the fish may have to "learn" to use the new material.
"[Fish] can’t be kept from breeding if healthy," points out Wright Huntley.
Nematolebias (Cynolebias) whitei is traditionally a peat diving fish, and seem to breed best when the fish can submerge themselves completely in the peat when vertical. "I often use a 5" flowerpot," says Wright, "nearly full."
But Wright doesn’t necessarily use peat as a spawning medium. He gradually reduces the amount of peat in the container and adds a sinking mop on top of it. The fish keep diving through the mop to get to the peat. Eventually, there is no peat in the container, and they have learned to spawn in the mops alone.
Using mops rather than peat keeps the spawning tank cleaner and makes the eggs much easier to find. The eggs can then be picked and stored on peat in the usual way.— G.C.K.A. Newsletter, November 2001 Return to top of page
A Technique for Catching Fry
Catching a number of small fry from a larger container can be quite a chore. Many fishkeepers have spent frustrating hours with a spoon, a siphon, or a net to little avail, and longed for a quicker, simpler method.
The following technique, described by Gary Harman-Hobbs, may take a bit of time, but it may be worth a try as you try to catch those quick little wrigglers.
The entire concept is based on the fact that given the chance, most fry, like brine shrimp, will swim toward light.
If you’re dealing with a bucket or container full of "gunk" or peat with fry, try this. Leave the container alone in the dark for a couple of hours. Later, get yourself comfortable nearby, with a fine-mesh net, a small bright lamp or strong flashlight, and a container of water for the fry.
Shine the light along/down the side of the container so it penetrates 2-3 inches or so, leaving the rest of the water dark. Wait a while. The fry should gradually swim up from the bottom and dark sides toward the lighted area. Net them out. Repeat until the container appears to have no more fry in it.
If you have a number of fry in an aquarium, and want to remove them or separate them from their parents, a slightly different approach may prove useful. Go to your local needlepoint/hobby store and purchase some plastic needlepoint mesh with an appropriate grid size. Cut so the material is slightly higher than the high water level, and somewhat wider than the narrow width of the tank. Wedge snugly into place.
Leave the tank in the dark, providing a light source at one end, and wait. The small fry should easily find their way through the mesh toward the light, leaving their parents behind in the darker area. Net out fry and move as desired. — G.C.K.A. Newsletter, August 2005 Return to top of page
A Couple of Experiences with Coconut Coir
In recent years, coconut coir (fiber) has become available to the aquarium trade, and has proven useful as a breeding material for soil spawners. The following reflects the experience of two noted killikeepers with this material.
"I have used two types of coconut coir (fiber)," says Curt Smith. The first, from Rolanka of Georgia, was brown and fibrous. He found that it sank in water at about the same rate as eggs, which made it a poor choice for attempting to rinse away the medium away to find the eggs. Effective cleaning required several fillings of water and pour-offs to rinse away the debris, making peat more practical. Egg production seemed comparable between the two media.
The second batch of coconut material was a reddish colored, ground coconut shell. This material developed a strong odor after it had been wet for a while.
Tony Terceira has reported different results with coir. He mixes his half and half with Jiffy 7 peat pellets. "I have incubated up to 6 months [in this material] with no problem," he says. He stores the coir in a tub like peat, only wetting what he needs. Preparation is simple, just rinse it prior to using. He never has boiled it. "I like [coir] because it keeps the peat looser." Also, since it is basically neutral, it doesn’t cause the pH to drop as quickly. — G.C.K.A. Newsletter, October 2005 Return to top of page
Condos for your killies?
Killie keepers use a variety of containers to store their water incubated eggs, but a number of killie breeders have found that a plastic, multi-drawered parts storage cabinet, available in most hardware departments, serves admirably for egg storage.
Al Boatman of Florida uses a 6 x 10 drawer size cabinet for incubating his killie eggs. Five drawers are devoted to each species, allowing storage space for a dozen species.
At the top of the row he puts a label with the fish name and location code. The first, labeled tray, contains hatch water mix. When eggs in this drawer begin to eye up, they are moved to the second drawer, which contains regular water for hatching. The third drawer contains new hatchlings, with a sprig of Java Moss or Hair Algae. The fourth drawer is for free-swimming fry, and the fifth is an extra, used for replacement as necessary. Water in the drawers is changed every second or third day.
To move eggs from drawer to drawer, Boat uses a disposable plastic pipette. When fry become too big or there are too many for the "incubation/hatching condo" they are moved into larger growout containers.
These "killie condos" are space efficient, and handling and cleaning the drawers is easier than working with petrie dishes.— GCKA Newsletter, July 2002 Return to top of page
Observations from the experts …
Dangers to Your Killie Eggs
"The main danger to killie eggs," says Monty Lehman, "is fungus spores that … can ruin all killie eggs, even good ones."
The late George Maier had the theory that fungus on killifish eggs was a secondary problem, following a bacterial attack. Either way, fungus on killie eggs can be a real problem.
The best chance to get fry from your killie eggs is to begin with strong, fertilized eggs in clean water. If they turn white or cloudy soon after being laid, nothing will prevent them from eventually succumbing to fungus.
Fungus can happily destroy even good eggs, if given a chance. Fungus spores are present in the water all the time. They need two things to multiply: a food source (the eggs), and light. Acriflavine is a copper compound that, in sufficient strength, will kill or reduce fungus activity. Methylene blue blocks the light source, if it is used in a strong enough concentration (dark blue water).
If you use soft water to incubate your eggs, Monty recommends the use of Acriflavine. For those with harder water, Methylene Blue and careful attention are recommended, since Acriflavine does not seem to work as well in hard water.
Wright Huntley prefers a 50/50 Acriflavine/Methylene Blue mixture, a very pale green. This is changed out with 50% daily water changes. "The Methylene Blue seems to enhance oxygen transport and makes the eggs develop better." Wright also uses Ramshorn or Pond snails and Java Moss in his egg containers, which are kept in a dim (not dark) area. These help to keep the bacteria counts down.
Sean Monson has found that a stock solution of Maroxy and Methylene Blue, just enough to tint the water, works well for him. Maroxy breaks down quickly, so you will need to mix up a fresh solution for each use.
Good eggs sometimes absorb some of the Acriflavine dye, becoming lightly yellow tinged, while remaining clear. Move such eggs back into clear water and some of the dye will often leach back out. Too strong an Acriflavine solution can kill some eggs.
Change the water in your incubation containers at least every other day, and remove any cloudy or fungused eggs immediately. As the eggs eye up, move them to a container of their own; if a newer egg goes bad, you may lose the good ones too.
A few other observations on eggs from Monty:Clear eggs that are twice normal size (from the same female) are usually infertile.
Eggs that easily float are infertile.
Any egg that is cloudy, milky white, or has a milky spot in the center is infertile.
If an egg seems soft and deformed, it may be a bad egg, or it may be newly laid. If the latter, it will firm up in a short while.
— G.C.K.A. Newsletter, June 2005 Return to top of page
Dominant Males Get All the Girls? Not Always!
Many variables are involved in breeding killifish: the number of breeding sites, the age and fertility of particular fish, size of the aquarium, the number of fish in a breeding group, how well they have been conditioned, etc.
Many killikeepers have long assumed that in breeding groups, the dominant male was consistently achieving breeding success by driving away competing males from the breeding site. However, anecdotal evidence seems to counter this view.
"Much of the time the dominant male only seems to get the girls," wrote Jay Moylan in a message to the KillItalk mailing list.
In most species, the alpha male provides social discipline, marks and protects his territory, and hugs the breeding spot, usually siring most of the offspring. However, subdominant males still produce a surprising share of the actual offspring, sometimes slipping in to spawn when the dominant male is busy elsewhere, sometimes spawning with willing females elsewhere.
"I had an actual case myself," Jay continued. "I had two pair of Chromaphyosemion splendopleure doing quite nicely in a 2-1/2 gallon tank. They were producing many eggs and fry." When the alpha male began to really pick on the beta male, Jay removed the beta male. Egg production basically stopped.
Other aquarists have observed subdominant males in a number of species taking the opportunity to spawn when the dominant male was otherwise engaged.
There has long been the belief that group spawning produced a wider genetic variation in the offspring than that produced by controlled pairs breeding. Perhaps some of the observations of subdominant male breeding behavior help to confirm it.— G.C.K.A. Newsletter, August 2002 Return to top of page
Egg Color
Most killie eggs are more or less the same; fairly round, clear or pale amber eggs of various sizes, laid singly. Many killifish eggs are golden or honey colored when laid. Although laid clear, many annual eggs become dark brown, a combination of internal development, peat stains and (with some eggs) adherence of peat particles to the egg itself.
"The Golden Pheasant (Callopanchax occidentalis) … is true to its name – from egg to death," says Bob Rueven. They lay a golden egg. Even the fry are a bit golden.
"Moema sp. "Peru" lays non-adhesive orange eggs," reports Dan Katz, and "Capellolebias brucei and C. dorsimaculatus lay eggs which range … from nearly colorless to light yellow to orange and brown" all from the same spawn.
"The largest disparity in color I have seen is the difference in color of Lamprichthys tanganicanus eggs," says Lee Harper. Eggs collected by Joe Bulterman were orange; those collected by Lee from the same strain of fish were nearly colorless. All hatched fine, so viability was not in question.
Egg color may vary by or within species, but it may also be directly influenced by what the fish are fed. The yellow-orange color can be affected by the water, or by lipid soluble compounds in fish food, such as B-carotene, Astaxanthin and Anthocyanins. Both Cyclop-eeze and Golden Pearls contain Astaxanthin.
"I’ve noticed since I’ve been feeding Golden Pearls (500ppm Astaxanthin) [that] more .. eggs are colored," writes David Lains. "Simpsonichthys sp. Bahia eggs are almost red. Some of my Aphyosemions have gone from clear to tan." But c egg color does seem to be variable even in a group of fish. In zebrafish (Brachydanio rerio) fed Golden Pearls, group spawning can result in eggs that range from clear to orange. "The males are very easy to sex due to their red fins," says David.— G.C.K.A. Newsletter, September 2003 Return to top of page
You know they’re there … but you can’t see them …
Finding Eggs in Peat
By Wright Huntley, Fremont, California
Finding eggs laid in peat is really easy, if you go about it in the right way. This is a mandatory skill for the adept breeder, as gestation times vary and finding the state of eye development is crucial for good hatches without belly sliders.
Get a good halogen reading lamp, preferably 50W or more. Pleat gets dumped into a white, shallow bowl with smoothly-rounded, very low sides and mostly flat bottom. Position the lamp across the peat from you so it and you are seeing the peat from about 45 degrees. Direct sunlight can substitute for a lamp.
Fluff the peat and gently break up any clods. I use a good pair of tweezers, with smooth, rounded tips, as my stirring/dragging tool. A single, pointed (Japanese style) hashi (chopstick) works well too. Move the peat to one side of the bowl, and gently flatten it with the backs of your fingers. I use a mechanic's (jeweler's?) loupe, clipped to my glasses frame, as my eyes are old and tired. Look for eggs in the smoothed surface first. If there are a lot, you will see them right away.
If not, start dragging small amounts of the peat across the bowl to the other side, watching for the yellowing gleam of an egg against the bright white bowl bottom. I can mix a single egg into this much peat (single pellet) and find it in less than 10 minutes with about 90% certainty. By taking a thin bit of peat at a time, and scattering it over the surface, the bowl acts sort of like a light table to make the egg obvious. You can do this really quickly, once you have found an egg or two and have trained your "pattern recognition" in what it is supposed to detect.
You are looking for both shape (round) and color (golden). Some baled peat has oval seeds in it that look too much like eggs. The Jiffy pellets don't. Most peat never contains perfect spheres, and most eggs don't get stained too dark until they have dried in the peat for quite a while. Later, the gold ring around the eye glistens in a unique way to help find even darkly-stained 9-month Cynolebias eggs.
When that gold ring surrounds each black eye, completely, on more than 2/3 of the eggs you find, it is time to dunk them. Waiting just ups the chance of poor development and belly sliders.— G.C.K.A. Newsletter, January 2001 Return to top of page
Floating that mop …
You’re making mops for use with your plant spawning killifish, and don’t know how to make them float. Here are some proven ideas from aquarists.
"Use a piece of Styrofoam and a rubber band," says Robert Goldstein.
"I use mostly unwashed wine corks," says Wright Huntley. "For a larger float, the long skinny foam swim toys ["noodles" – Ed.] are good…. Cut a 1/2" thick slice and you have a good permanent floating donut. I like them as rafts for Rivulus to climb out on."
Jim Randall uses very clean Styrofoam meat trays. "I cut circles out of them, then make a hole in the middle with a slot to slide the yarn in."
"If you check your local Beer/Wine making store, they have several options," points out Drummond Howard. "’Real’ cork, pressed cork (kind of like particle board) and synthetic cork (hard rubber or soft plastic). The plastic corks should last a lot longer and should be easier to clean and disinfect. However, I’m all for recycling used wine corks and empty 35mm film canisters " – place a strand of yarn over the edge of the canister, then snap on the lid.
There you have it: several easy, cheap ways to make floats for your spawning mops!— G.C.K.A. Newsletter, May 2003 Return to top of page
Fry the Easy Way — (with apologies to Julia Child)
By Donna M. Recktenwalt
A major fascination about many of the killifish we keep is the way they reproduce, but breeding them can be a lot of hard work, especially for those species that require long incubation times.|
What if you want to keep and breed killifish with a minimum of effort?
With some species of plant- or mop-spawning fish, it can be done.
Start out with any size tank, densely planted or well filled with fine leaved free-growing plants such as hygrophilia, hornwort, watersprite, or java moss. Add a slow running foam filter, either external or internal. Introduce the fish, feed well and do regular partial water changes; then watch fry of various sizes begin to appear.
Sound too simple?
For some species of killifish, particularly the annuals, this approach would be next to impossible; for others it is nearly ideal: the fish fertilize the plants; the plants host a colony of microflora and fauna and provide sites for egg-laying and cover for the fry; which feed off the microscopic life.
Supposedly many European killikeepers routinely breed their mop-spawning killies this way.
“I have a 20 gallon high tank that is about 3/4 full of java moss,” says Shane Essary. “I put the pair of fish that I want to spawn into the tank …. Pretty soon the tank is full of babies that get really big without having to feed them [heavily on] baby brine shrimp.” Shane has used this method successfully for A. scheeli. For A. abacinus, he substitutes mops for the java moss but still lets the eggs hatch naturally.
“I have had good luck with A. celiae celiae, letting them breed in a well planted tank and not picking eggs or rescuing fry, also with E. dageti, using java moss,” reports Harry Kuhman.
Donna Recktenwalt has been raising A. chaytori Ngabu and A. mirabilis Takwai in separate densely planted colony setups. “I get as many fry from the tanks as I do from collecting and incubating the eggs,” she says. “I regularly find fry of various sizes in with the adults. The parents seem to ignore them entirely.”
“Almost all my Epiplatys annulatus will allow young to survive,” says Lee Harper, “and a trio of Pachypanchax omalonatus has shown tolerance for young fish. Diapterons in general will not.”
“I’ve had this experience [tolerant parent killifish] with E. fasciolatus (big time! we’re talking hundreds from four adults in a plant and algae choked 40 gallon tank), E. dageti, and (to a much lesser extent) A. australe,” says Richard Sexton.
Other species that aquarists report have shown tolerance for their fry include A. ogo ottogartneri; A. coeleste, A. aureum, and A. citripinnis.
For particularly troublesome species, a variant of this method has been used successfully by some. Instead of simply filling the tank with plants, pack it nearly full of java or sphagnum moss, leaving only a little space around the outside for the adult fish, and a small depression at center top for the fry. The parent fish will spawn in the java moss and the hatching fry will gravitate to the depression at center top, where they can easily be removed for growout in a separate container.
This doesn’t always work, but may be worth a try for fish that are highly aggressive, or that regularly prey on their young.
— G.C.K.A. Newsletter, December 1997 and March 2002 Return to top of page
Harvesting … gravel?
A number of substrate spawners will readily lay eggs in anything on the tank bottom, be it peat, mops, mulm, or gravel. Obviously, a spawning medium that you can easily handle to harvest eggs is preferable, but what if you want to recover eggs from gravel?
Try this technique. It takes patience, but may work even in tanks that also contain plant spawners and possible fry.
Using a gravel vac, gently stir up and "clean" the gravel, running the outlet water through a fine mesh net. Dump this collected "grunge" into a container of clean, conditioned water like that from the harvested tank. Let settle, then stir gently and as you find them, carefully remove eggs (and possibly fry as well) with a turkey baster or eye-dropper.– G.C.K.A. Newsletter, June 2003 Return to top of page
Hatching Annuals – A Method to Try
One of the problems encountered by any who incubate killifish eggs in peat is separating the fry from the peat once they have hatched. To some breeders this is unimportant, but others may want to move the fry into cleaner water, or remove the peat completely.How to do it? Richard Dippold has this suggestion.
Take a dark plastic container with a lid, dark enough so that light can’t pass through it.
Cut or drill a 1/2″ hole in the side of the container, 1/2″ below the water level planned for the grow-out tank
Put something in the container to weight it down.
Place the hatching container in the growout container, making certain that the water surface is above the cut-out hole.
Plug the hole with a small piece of cloth.
Pour the peat to be hatched into the container, and put on the lid.
Once the peat is wet, take the cloth out of the hole.
Hatching fry will swim toward the light, out of the hole, and into the growout container.
Most of the peat will stay inside the hatching container: floating peat above the hole, sinking peat below. This method will separate most of the fry from the peat without effort by the aquarist, although it may take a day or two. Plants in the growout container may prove useful too.
— G.C.K.A. Newsletter, September 2004 Return to top of page
Hatching Out Blue Gularis
One killikeeper, who has been unable to successfully breed Nothobranchius, regularly raises fairly large batches of Blue Gularis (Aphyosemion sjoestedti).
His secret? For either Blue Gularis or Dwarf Red Gularis, separate the males from the females for a week, feeding them well. Put the breeders together in a dark 10 gal. tank with several mops that extend all the way to the bottom. Collect (pick) the eggs by hand in the evening.
For water, use 10% from the spawning tank, 90% distilled. Place the eggs into small glass dishes with about 1 cm of water, adding just enough peat to lightly cover half the bottom of the dish. Incubate at 74ºF. Every other day, pour off most of the water and replace.
Usually, only a few of the collected eggs are infertile. If you look closely, you can see the developing fry. The eyes will be visible in about 2 weeks, and in a week or so more, the fry hatch, virtually all at the same time.
Eggs incubated and hatched this way grow rapidly and uniformly. At about 6 weeks, separate out the really nice males and heavily cull the remainder, then distribute into larger tanks as necessary for growout.— G.C.K.A. Newsletter – November 2003 Return to top of page
Hatch Water – A Good Topic for Discussion
A lively topic for discussion among killikeepers who breed water incubating species is the appropriate hatch water. There are several possibilities.Regular tank water (from the breeders’ tank)
Clean conditioned (dechlorinated) water, or straight tap water
Hatch water solution
“Peat” water
For most people, using either tank water or conditioned tap water is the simplest answer. Clear, conditioned water is simply aged water or tap water that has been dechlorinated.
“Tank water has instant, ready to eat food for fry,” points out Bill Shenefelt. “If there is some cover, and some food, and sufficient water, you can wait a week before feeding, and start feeding a decent number of hatched fry. I rarely move them from the two or three gallon tank or shoebox in which they hatch until they are about a quarter of an inch long.” Water from the parents’ tank also assures that there will be no temperature or chemical shock to the eggs or fry. However, it does add some risk due to potential bacterial bloom or fungal growth.
Many killikeepers use a hatch water solution. The late Ed Warner, in his book, Success With Killifish, offered a recipe that has worked well for many.
Ed Warner’s Hatch Water Solution
1 gallon water
1 drop Aquari-sol
1/2 tsp. non-iodized salt
5 drops Methylene Blue
Aquari-sol is an anti-fungal agent. Methylene Blue is an unstable dye that is absorbed by any weak, infertile or dead eggs, turning them dark or milky blue, thus allowing for easy identification and removal. Some aquarists also claim that it reduces the light available to the developing embryo, a plus since most killi eggs are sensitive to light.
A number of killie keepers use Methylene Blue, Aquari-sol, or Acriflavine as hatch water additives, either alone or using variants of the Ed Warner recipe.
"If I water incubate," says Sue Katz, "I use very fresh tap water that I dechlorinate and add Acriflavine."
You might also try using "peat water." This is simply distilled or R/O water that has been soaked with peat for a few days. Strain to remove the peat, then to each half gallon add a drop of anti-fungal agent.
As useful as hatch water solutions may be, they are not cure-alls. Not all incubation techniques or hatch solutions will work for all species.
"In my experience," says Nevin Aspinwall, "the Ed Warner solution just doesn’t work for A. maculatum. The eggs just die."
You might want to try a hatch water solution for your incubating eggs. But in some cases, letting nature take its course seems the best solution.— G.C.K.A. Newsletter, June 2002 Return to top of page
How many fry in a growout tank?
Occasionally a killikeeper will ask, "what kind of population densities are appropriate for growing out fry?" This is a valid question, since crowding – and the increased chemical and hormone levels resulting from it – can directly inhibit fry growth.
With more fish per gallon, water quality becomes ever more critical. Heavier populations mean more food, more competition for food, and more pollution. Obviously, we need to maintain clean water and good conditions for fish, especially for growing fry. This requires good filtration and regular water changes.
But we also need to remember that surface area is also important. "I raise my [Fundulopanchax gardneri] fry in plastic shoe boxes," says Br. Paul Jablinski. "I only put in about an inch of water, which gives me about 70 square inches of surface area. I keep about 20 half-inch fry in each box, and when they reach an inch, I cut it down to 10 fish per box. I change all the water I the boxes about twice a week."
For some species, these smaller quarters may work very well, but if you have big spawns of fast growing fish, you may need larger quarters, and soon.
A population of "140 F. walkeri in a 20 gal. tank is really tight, if they have much size to them," says David Ramsey. This species sexes out when fairly small, so watch your sex ratios closely. You may find that you can pick out 20 or so males and 30 or so females, and then thin out the rest. That will leave 50 or so fish to grow out in the 20.
"Blue Gularis [Aphyosemion sjoestedti] are a completely different story," David continues. They grow fast and eat heavily, so really need big quarters with heavy duty filtration. "I have 30 in a 29 gal. tank., and at 2-3" they are terribly overcrowded." Changing 10 gallons each week and continuously running 2 outside power filters doesn’t keep up the water quality.— G.C.K.A. Newsletter, July 2003 Return to top of page
Advice from the Experts
Incubating Eggs … Several Methods
For many killikeepers, the challenge of breeding only begins when the fish spawn. Hatching the eggs and raising the fry can cause problems all their own. Here are a few tips from Lee Van Hyfte, thanks to the KilliTalk Mailing List.Change the water the eggs are in every few days if you can. Eggs are living tissue and can give off waste products and CO2.
Use clean aged water from the same source as the parents, not from their tank! Fish wastes are in their water.
Pull the spawning mop out every 4 days or so and incubate the eggs (in the mop) in a 1 gallon jar full of aged water with just a trickle of air running opposite the mop.
Keep containers covered at all times. Dust settles in egg containers, as well as on your TV.
Fish eggs don’t lie on the bottom in the wild. They are suspended among the plants and debris.
“My father took this point to an extreme,” says Lee, placing eggs on a screen glued to PVC pipe. This was then placed in a dishpan with a slow circulating filter system. “The results were fantastic … He even raised fry that way with good success.”
Lee lays eggs on a 1/4″ bed of fine grade peat in 2 in. of water. This gets the eggs off the bottom and away from each other. Tannins in the peat act as natural antibiotics and fungus inhibitors.
Throw a little Java Moss in the incubation container. Better yet, place the eggs you pick on it. This gets them off the bottom.
Say NO to flake foods. Use high quality live and frozen foods. In an experiment, Lee compared the results of flake and live foods on breeding fish. The difference in hatch rate from two identical batches of Blue Gularis eggs was 15% for flake food, and 80% for live food.
“Most importantly, Don’t Give Up!” Every killikeeper has losses and unconquerables. This is half the fun, making success that much more rewarding.
— G.C.K.A. Newsletter, May 2003 Return to top of page
Advice from the Experts
Incubating Eggs on Peat … Several Methods
Most killifish species fall into either the "plant spawning" or "substrate spawning" groups, and handling and hatching the eggs is fairly straightforward. There are a few species that "switch hit," willingly spawning anywhere they have the chance. And there are a few species that seem to cause breeders problems, no matter how carefully they do or do not hnadle the eggs.
For some of these, incubating the eggs on wet peat has proven a useful technique.
Al Anderson of Indianapolis, Indiana, has been successfully breeding tropical and killifish for longer than many of us want to admit. Over time, he has developed techniques that may prove useful if you’re having problems.
Al suggests the following for peat incubating eggs.Method 1
Boil some peat* (see note at bottom).
Pack it tightly in a covered container (a petrie dish or small margarine container).
Rinse the harvested eggs in clean tank water slightly tinted with acriflavin.
Let the eggs rest in shallow clean tined water. Remove any white or fungused eggs as soon as you see them.**
After 3 or 4 days, place the eggs, one at a time, on the moist peat in the dish.
Cover the dish. Store it in a warm place (80-85ºF) and wait for the eggs to eye up.
Method 2
Boil the peat.
Squeeze it in a net to get out most of the water.
Place in a folded newpaper sectio novernight.
Place the peat and eggs into a plastic bag, fold the bag, and store at 80ºF for 2-3 months.
Method 3
Half fill a petrie dish with water that is 20% Ringer’s solution.
Add eggs and put on the cover.
Remove white eggs daily for a week.
Store in an area where they will remain at 80ºF for three weeks. If they are eyed up, hatch them by putting the eggs in tank water in a jar with a loose fitting cover. Use water from a tank that has peat in it.
Place the jar in the bottom of a deep tank. The fish that are ready to hatch will be swimming in an hour or less. This technique will help to avoid belly sliders.
- You can use either boiled peat, close pore sponge, or multiple layers of paper towel on the bottom of the the incubation container. Your choice.
** Note that with albino fish the eggs will often be white. Don’t discard these.
– G.C.K.A. Newsletter, February 2004 Return to top of page
It’s in the Genes….
A Quick Course in Inheritance
Not too long ago, a question was asked on the Killietalk Mailing List about inheritance of the factor for blue tails in Nothobranchius guentheri.
"It is probable that the blue tail color is due to a mutation in a protein that makes the typical red pigmentation in the tail," Eric Lund replied. "A male with two copies of this mutated gene would fail to produce the red tail pigmentation, thereby unmasking an underlying blue tail color....
"The bluetailed mutation is recessive, which means that if you continue to line breed you will get only males with blue tails. If you cross a blue tailed male to a female of the normal aquarium strain you should get only males with red tails in the next generation (F1), but the following generation of offspring would be 25% blue tailed."
In clarification, genetically each parent contributes a single set of genes to their offspring, resulting in two sets of genes in the young. Designating "R" as the normal (dominant) gene for red tail, and "r" as the recessive gene for non-red tail (blue), the following results:
1. If you breed a blue tailed male ("rr") to an aquarium strain female ("RR"), their offspring will all be "Rr" (red tailed, carrying the blue recessive factor).
2. If you then breed the resulting fry ("Rr"), brother to sister, you will get 25% "RR" (pure red tail), 50% "Rr" (red tail, blue recessive), and 25% "rr" (pure blue tail).
"The trick to fixing these sorts of strains," says Eric Lund, "is to remember that the females carry the genes too, but they do not show what their phenotype is. If I had a killie strain with a recessive trait that popped up fairly frequently and I wanted a true breeding strain from it, I would do the following:
1. Isolate each female separately in a spawning tank.
2. Breed each female only to males showing the recessive trait.
3. Collect and label the spawns from each female separately.
4. Raise the offspring from each female in separate, labeled containers.
If the trait you’re selecting for is from a single recessive gene and the mutation is common enough that you had at least one homozygous recessive female ("rr"), her male offspring should all be the same. Fish from containers where all the males show the trait will breed true.
If all the tanks have only males of the normal phenotype, then you didn’t have any homozygous recessive females as breeders. This is because the gene is quite rare and you didn’t have enough females.
If tanks of offspring from separately bred females have males with both phenotypes, then the trait you are selecting for is not due to a single recessive mutation, and other tactics are required to produce a strain that will breed true.— G.C.K.A. Newsletter, May 2001 Return to top of page
Java Moss – Mops?
Here’s a different idea that might be worth a try. Thanks to George Davis of Wilmington, Delaware, via the Killifish (electronic) Mailing List.
"I had not used artificial spawning mops ... simply because I was lazy and liked the more natural Java Moss approach," George Davis wrote recently. "I rarely saw eggs with most of my various Aphyosemions or Epiplatys, but got continuing natural tank spawns. However, of a half dozen adult F. gardneri Misaje he was down to only one female.
"Yarn mops seemed interesting because of the tight spots. Java Moss will spread out in a tank and let the parents go through on an egg eating mission. So I figured, let’s make a Java Moss mop."
George took a handful of Java Moss and tied a knot tightly across the middle with a piece of twine. This produced a neat mop, tight in the center, with fairly loose ends, and allowed the fish a choice of where to deposit their eggs. The mops were left with the breeding fish for several days, then removed to a shoebox with clean water for incubation and hatching.
In about two weeks he found the first fry, which he started off on infusoria and microworms.
Java Mops are easy to make, easy to use, and easy to rotate from spawning tank to rearing tanks. They might be worth a try for those fish that just don’t seem to be spawning, or that are eating their spawns.
But "be sure," George cautions, "to rotate mops only through a single species so that you don’t get eggs crossing over to a different tank."— G.C.K.A. Newsletter, November 2001 Return to top of page
Light Change Triggers Spawning?
Aquarists have long known that sometimes apparently unrelated changes in their environment can trigger spawning in some species of fish. Killifish are no exception to this
"I recently had a minor air-conditioning leak in my basement," reports Mike Brem, "so I put on all the lights in the basement … near the A/C to monitor the water accumulation. I figured with all the other lights (incandescent bulbs in an unfinished basement) left on …. I could switch off the fluorescent fixture over the fish tank rack and give the electric bill a rest. All tanks that were normally lit from above were now illuminated strictly from the side.
"Several of my infrequent plant spawners must have enjoyed this change it seems, because they produced quite a few more eggs than in recent weeks."
Mike admits that it might have been one or several of many other factors that could have triggered spawning – changes in barometric pressure (rain), reduced light, his increased presence in the fishroom, etc. – "but I still wonder about the lighting change…. could light shining into a tank from the side be interpreted as a sunrise or dusk period?"
There may not be a precise answer to Mike’s question, but other aquarists have noticed a relationship between lighting conditions and egg production.
"I have several species that produce … more [eggs] in dark conditions," observes Gary Elson, "although they don’t necessarily inhabit dark biotypes in the wild. I put it down to reduced egg eating rather than more actual spawning."
"It may be that during the diurnal cycle, some killies/fish just like the sun on their backs," theorizes Mike Delraso. He has noticed that some killies in tanks that are sun-lit from the side will hide until the sun passes the window, and a more diffuse light illuminates their tanks. "The only killies that I have had that never responded well to full lighting were Diapterons … [they] never seemed to like light in my tanks, especially A. abacinum."
On the other hand, Wright Huntley’s experience is that Diapterons seem to hide because they are "so damned mean to each other. I seriously doubt if the light level has any other effect than to make them visible. When [I had] a single pair and they were in the mood, I never noticed the least bit of light shyness. Put a trio or, especially, two or more males in a tank and they all head for the darkest corners. [They are the] nastiest fish, per pound, I have ever kept!" This phenomenon, he suggests, may also explain the reclusiveness of some other quite attractive species.— G.C.K.A. Newsletter – February 2004 Return to top of page
More on Eggs … from some of the experts
We all know that handling killie eggs during the incubation period can be problematic. Eggs disintegrate, turn white or cloudy, fungus. In some cases we can’t prevent these occurrences, but for water-incubating species there are some steps we can take that will reduce the incidence of egg loss.
"I don’t think it’s possible to pick an egg and put it in the storage container without bringing bacteria in with it," says Jay-Scott Moylan. He uses Methylene Blue as a bacterial agent in hatching water. "I also put a couple of drops in my 2-liter bottle baby brine shrimp hatchers for the same reason."
George Morris agrees about handling eggs. "I find that I get much better hatch rates with eggs that I’ve never touched. Transfer the mops to a hatching tank, or remove the breeders from the spawning tank…. Do not pick the eggs."
"A spring of Java Moss is … a great germicide" in a hatching container, says Wright Huntley. Java Moss carries infusoria, which feed on free-swimming bacteria. As an experiment, try setting two glasses of clean water in a warm place for a few days. Put a bit of Java Moss in one. Add a drop of Liquifry to each, or a tiny bit of food. "The bare one invariably goes cloudy for me," Wright says, and the one with Java Moss is clear. "It’s my guess is that it’s the microcritters, living on and near the Java Moss, eating the bacteria."
"Really fresh eggs," Wright continues, "don't always survive handling well, but after a few hours of hardening, they are tough as nails.... The ones most likely to fungus, if handled, are the softer, fresher eggs."
In some cases, more drastic measures are successful. Lee Harper has used water containing chlorine (right out of the tap) to incubate Rivulus xiphidius eggs.
Al Anderson points out that temperature of incubating eggs can make a major difference. "A lot of people fail to notice … is that when collecting eggs they should be placed into the same temperature water that they are taken out of.... As little as one degree can make a difference."
Another factor to consider, he says, is diapause. Each egg can go into as many as seven of these resting period. Heat, temperature, the amount (or lack) of oxygen, and age of the breeders can all affect diapause. Mostly, it is soil spawners’ eggs that go into diapause, but it can happen to some of the plant spawners as well. "I have had Fundulopanchax gardneri and Aphyosemion australe go into diapauses for as long as six months and hatch into good looking, healthy fish," he says.— G.C.K.A. Newsletter, September 2005 Return to top of page
A technique with … Nothos
As most fishkeepers know, there are many individual techniques and successful ways to breed many species. One killifish breeder has found success with the Nothobranchius species by following these steps.
1. Several pairs are kept together. Tank size ranges from 10 to 30 gallons.
2. Tanks are bare bottomed, with the outside of the bottom painted. Decorations include driftwood and potted and floating plants.
3. The fish are kept in tap water (150-200ppm KH and GH and 7.8 pH) unless they’re being spawned. For breeding, the water chemistry is slowly changed to the chemistry that species needs. N. guentheri, N. rachovii, N. orthonotus and N. korthausae have all been bred successfully in tap water.
4. Fish are spawned over 2 or more containers of peat per tank, with peat 1" deep.
5. Peat is collected every week or two, and dried between newspapers until it feels like moist chocolate cake. Squeezed between two fingers, it will release a drop of water. The peat is fluffed up for storage.
6. The peat is fluffed up before storage (with air) in plastic bags at room temperature (75ºF). Check the bags regularly to make sure the peat is moist enough.
7. Hatch in large plastic shallow containers in 2" of soft, acid water (4-5 KH and GH and 6.5 pH), with a big clump of Java Moss for extra food and security.
8. Feed greenwater for 2-3 days, along with baby brine shrimp. Once you can see orange bellies on fry stop feeding greenwater.
9. Once the fry are strong enough and eating baby brine shrimp well, start adding small amounts of tap water, thus slowly changing the water parameters. This aids in maintenance and in disease prevention.
Nothos don’t like much water movement, either as fry or as adults, so plan to use small filters bubbling very slowly, adjusting flow as needed.
Diet is important for Nothos. They like live food and shouldn’t be left without it for too long. Chopped tubifex or black worms are a great food for getting lots of eggs. — G.C.K.A. Newsletter, October 2005 Return to top of page
A Different Spawning Medium – Oak Leaf Mold
Allen John, writing on the KillieTalk e-mail list in February 2001, initiated a discussion on the possible use of oak leaf mold for spawning annual killiefish.
Killikeepers have long known that adding oak leaves to the tanks of acid water loving fish, such as certain Rivulus, improves water conditions and makes the fish more at ease. However, using the "mold" form was something a bit different.
"I have experimented with this material in two different annual killifish breeding containers," reports Allen. "There are some good things associated with this product, ... but there are a number of drawbacks. Here are my observations."Positive Effects of Oak Leaf Mold
1. Allen’s tap water measures pH 7.8 with a TDS of 330. After a week with the oak leaf mold, the water in his breeding tanks dropped to pH 6.6 and TDS 240. Peat pellets (which Allen normally uses) have minimal effects on these measurements.
2. The oak leaf mold seemed to remain in the bowl better, thus the tanks remained cleaner.
3. The material is not very absorbent, thus dries out quickly.
Drawbacks Include
1. The material has a flaky texture, making eggs difficult to find.
2. The material tends to pack down, thus may be difficult for the breeding fish to penetrate.
3. Bubbles rapidly develop in it.
4. Because it dries quickly, there is less room for error in drying and storing.
5. The material reabsorbs water slowly; it floats upon rewetting. Separating the fry from it is difficult.
"The bottom line is that I think few of us will find this material an adequate spawning medium," Allen concludes. "However, since there seems to be some ion exchange capacity ... [it may be] a useful material. For me, I will ... use this material to condition my water to reach lower pH and TDS levels, but will continue to use peat moss for breeding."
"I successfully spawned both Cynolebias whitei and C. nigripinnis in an oak leaf substrate," reports Matt Hirvonen, "more or less by accident. I put a bunch of C. nigripinnis and C. whitei fry outside in 28 gal. Rubbermaid tubs last year from June to September. I added oak leaves ... to form about a 2 inch thick substrate." He seeded the tubs with paramecium and daphnia; there were usually mosquito larvae present.
"I basically ignored them until falling temperatures prompted me to bring them inside. By the end of summer the fish were big and beautiful and there were lots of eggs in the leaf litter at the bottom of the tubs, which by then included pine needles, small sticks, and a variety of other leaf types. I think the leaf substrate is probably similar to what the fish encounter in the wild."— G.C.K.A. Newsletter, February-March 2003 Return to top of page
Tips from the Fishroom …
“Peatless” Bottom Spawning
Tired of handling wet peat when you're breeding bottom spawners, and never being certain that yaou have eggs? Why not try something different?
Use a small flowerpot for the spawning container, and fill it with several bottom spawning mops. To harvest the eggs, simply remove the mops from the container and run them through your fingers. The non-adhesive eggs will usually drop right out.
It may take some "transition training" to get the fish used to this change in spawning media. Try spawning with peat in the container, then peat and spawning mops, and finally the mops alone. Most fish adjust fairly quickly to using this new media.
To store the eggs, stir into damp peat for storage as usual.— G.C.K.A. Newsletter, January 2001 Return to top of page
Peat Moss and Annual Killies
Keeping most annual species of killifish is not very difficult IF you know the species and HOW it should be kept. Probably the hardest part of keeping any species is finding out how to keep it.
An important component of keeping the peat spawning species is the peat moss itself.
You can obtain either "garden peat moss" or "fibrous peat moss." The precise type of peat moss may not be critical. "I have been fortunate in that every type of peat moss I have purchased has been ‘ok,’" says Roger Brousseau. He has used various kinds of peat with his fish, ranging from Canadian peat in the 2 or 4-cubic ft. bags, to garden peat in the 8 qt. sizes.
Once you have purchased your peat and brought it home, you need to prepare it for use.
"When I first started," Roger says, "I felt compelled to follow the advice of ‘experts’ and to follow their lead" by boiling my peat moss. However, peat need not be boiled. Just place some in the bottom of a five gallon bucket or other large container and fill with hot water. In about a week, all the peat will be on the bottom of the container.
"I generally leave the peat in the bucket, take out what I need for each individual aquarium and rinse it out in a fine net" prior to use, Roger says. The water in the bucket can be used as a conditioner for those species that need very acidic water in order to breed.
Leave the spawning peat in the aquarium for two to three weeks, then collect the peat and either squeeze it dry in a net before putting away for storage, or squeeze dry then place on paper towels for an hour or two before bagging it up. The handling depends on the species; some species require damper peat moss, others need it drier.
Most annual species in "Group B" require wetter peat moss and a shorter incubation time. For Roger, Cynolebias boitonei usually hatches out in three weeks at 72-75°F with peat simply squeezed once in a net.Resources: Brousseau, Roger. “Keeping Group B Species.” AquaTropica, Vol. 1, No. 2, http://biodec.wustl.edu~hrbek/aguatrR102.html
— G.C.K.A. Newsletter – March 2005 Return to top of page
Pre-wetting Peat Before Hatching
Problems with all of your annual eggs not being ready to hatch when you wet your peat? Try these tips, recently offered on the killietalk e-mail list, for simulating the natural trigger to hatching annual eggs.
Just like mud baking under the hot African or South American sun, peat in storage for long periods of time can get quite dry.
About two weeks before you intend to hatch the eggs, moisten the peat to the point that it is wet, but not dripping. You can use a spray bottle and mist it, or simply add a small amount of water to the peat before resealing the bag. This simulates the occurrence, in nature, of a small rainfall that often precedes the rainy season. About two weeks later all of the eggs will be eyed-up and ready for hatching.
Alternatively, this suggestion from Roger Brousseau. Wet the eggs for an hour. Drain, and redry the peat for an additional two or three weeks, then wet as usual for hatching.— GCKA Newsletter, February 2002 Return to top of page
Problems Catching Fry? A Couple of Suggestions
How do you go about catching fry or small fish in a heavily planted tank? This can be a problem, especially if you don’t want to tear up or strip down the tank in the process. Herewith, a couple of suggestions that might do the trick for you.
"I got a large net (14")," reports Doug Karpa-Wilson, describing his technique for catching a group of Cardinal Tetras, "and placed it across part of the tank." He left it there for about 10 minutes, then took a small net and used that to chase the fish into the larger one. "Once they were in the [large] net, they seemed happy ... [and] tended to stay put while I chased others into the big net." When he had most of them, he removed the large net. This resulted in less stress than usual to the fish.
"If your fish are ‘trained’ to come to an upper corner of the tank for feeding," Tom Roche suggests, "you may be able to use a plastic pitcher or scoop to get as many as half of them ... without using a net."
Or make a mini-minnow trap. Using a plastic water or soft drink bottle, cut off the top third, just past where the bottle becomes cylindrical. Punch a small hole in the side of the remaining bottom piece (to allow air out when you immerse it). Turn the top piece upside down and push it into the lower section. Bait it with something irresistible and place it on its side in the tank. There is no circulation inside the trap, so you will need to check it frequently or fry caught there for any length of time may die. "You may have to do this a couple of times," says David Sanchez, but you should be able to catch them all without breaking down the tank.— G.C.K.A. Newsletter, June 2002 Return to top of page
Raising Fry … suggestions from several successful breeders
"I’m having trouble raising fry …"
It’s a not uncommon complaint among killikeepers. But what can we do to improve our success rate with those hatching-out precious eggs?
Here are a few tips from some of those who have "been there, done that."Wright Huntley
Most of the time when I have had “mysterious baby deaths, a microscope revealed that they had velvet/oodinium.” Some precautions that may help are the use of Acriflavine (tint the water a very pale yellow color) and salt, 1 tbs. per 5 gal. water. Keep the light low, since Oodinium apparently photosynthesize.
Keep the unhatched eggs in total darkness. This kills off flagellates before they can infect the fry (until you expose them to tank water).
Keep the tanks extra clean. Use ramshorn snails and lots of Java Moss.
Remove any dead baby brine shrimp immediately.
Test the water with a pool chlorine test kit. Any faint color means that you need a dechlorinator, or a dechloraminator.
Dave Lains
My recipe for success with small fry (works with larger ones too):
1 container, 3/4 full with aged water
About a foot of airline tubing, filled with paramecium
1 Ramshorn and/or Malaysian Livebearing Snail
Top off tank with green water
Feed a few baby brine shrimp
The fry have lots of food items and places to hide. The snails, brine shrimp and paramecium all clean up after each other, and with good lighting you have an instant ecosystem that produces healthy fish, even in quart jars.
Bob Meyer
Dump the newly hatched (and almost hatched) fry into a one gallon container. Add about 1/4 gallon of greenwater and some Java Moss. Feed daily, and add greenwater when you think of it, up to 1/4 gallon a day. When the jar is full, drain down about 90% of the water and start over. A few daphnia help too.
After two weeks move the fish into a plastic shoebox and add more greenwater. Add snails at this point, and begin culling the fry for size and shape.
In another two weeks, move the fish to a tank and begin feeding heavily.
To recap: greenwater between feedings, frequent water changes, and cull mercilessly.
Bob Schwiegerath
Try placing the newly hatched fry into small polystyrene tanks containing a single layer of aquarium gravel, a small bit of Java Moss and some floating aquatic plants. No need to feed the fry for the first few days, as long as the plants aren’t too clean; they supply plenty of microscopic creatures for the first week or so. After that, transfer the fry to a larger tank and begin to feed live baby brine shrimp.
— G.C.K.A. Newsletter, August 2003 Return to top of page
Sex Determination in Fish
Sex determination and differentiation in fish is a common topic of discussion among aquarists. Just when in a fish’s life is its sex determined? At conception, when the sperm fertilizes the egg? At hatching? Or later in the fishes’ life, either as a factor of maturity, or as a consequence of environmental factors?
T. J. Pandian and R. Koteeswaran of the School of Biological Sciences, Madurai Kamaraj University, Madurai, India, decided to address this question and then published their research results in the paper "Lability of sex differentiation in fish."
The authors report that the process of sex determination and differentiation in fishes can be affected by chromosome manipulation during fertilization and the embryonic stages; by hormone levels during and just after hatching; and by temperature during the juvenile stages. In some fish gender can be altered by surgical and/or social changes during adulthood. It is known that fishes’ germ cells retain their bipotentiality to differentiate into male or female until sexual maturation, and that some species retain this flexibility even after sexual maturity.
Research with a number of species indicated that manipulation of gender is only possible during very specific, limited time periods.
Chromosomal manipulation – during insemination of the egg and early cleavages – is limited to a few seconds and minutes during and immediately after fertilization, and can result in a hatch of all females, all males, or complete sterility.
Hormonal manipulation is restricted to a few minutes just before or after hatching (using the immersion technique) or to a few days after hatching for ornamental fish. In food fishes (such as carp and salmon) this may be extended to a few months, when using dietary administration of hormones.
Thermal manipulation may be the simplest method for gender control in fish, although this has been shown to work only in the juvenile stages. This area has seen only limited research, results seem to indicate that lower temperatures result in females and higher temperatures result in males, with sex determination triggered by thermal control of certain enzymes.
Although sex manipulation in fish has been widely practiced in many commercially important species for some time, there is evidence that it may result in stunted growth, sterility, and other undesirable effects. It should be noted that no one species has been thoroughly studied using all the potential methods of gender manipulation.Reference: Pandian, T.J., and R. Koteeswaran. “Lability of sex differentiation in fish.” http://tejas.serc.iisc.ernet.
— G.C.K.A. Newsletter, September 2003 Return to top of page
Some Views On … Skewed Sex Ratios in Killifish
Imbalanced sex ratios in killifish fry are nothing new; hobbyists have long been encountering this problem in various species.
"In humans sex is determined by specific sex chromosomes, an x for female and a y for male," Allen Johnson reminds us. For reptiles gender is largely determined by environmental conditions (pH, temperature, various hormonal exposure during egg development). In fish, sex may be at least partially environmentally determined, with developing eggs and fry affected by pH, chemical, or temperature cues. Specific application of temperature and pressure on developing Tilapia eggs nearly always guarantees males for the aquaculture industry.
But for killifish, exactly when is sex determined? At the time of fertilization? During embryonic development? Post hatching, but before maturation?
"I personally believe temperature or pH are the predominant factors in sex ratio," Allen says. However, "in my experience ... females are most active in laying eggs immediately after being fed. ... It may be that eggs laid in the morning will be exposed to a longer light period and may develop into one sex, while those laid late in the day may develop into the other."
The age of parents may also be a factor on the sex ratio of the fry, observes Joe Weber. "In a number of species (in the Aphyosemion genus) I seem to get more even ratios as time passes" and the breeders age.
"Water temperature, pH, and hardness will all change the sex ratios of several species I keep," observes John Wubbolt. "For example, I raise Epiplatys annulatus. If I raise the fry in soft acidic water I get a majority of males. If I harden the water so that it's slightly alkaline and moderately hard, I will get more females. Same goes for Fundulopanchax gardneri N'sukka and Udi, and for Epiplatys dageti."
"In my trials with Aphyosemion zygaima," Gary Elson says, the results "boiled down to ... alkaline hardish (140ppm) water produced males ... while soft (but not necessarily acidic) water gave a closer to even sex ratio.... My A. ogoense 80/24 also give more females in tap/rainwater mixes than in straight tap water."
Those who have raised some of the Rivulus or Pterolebias species know of the "two per container" technique. Raised together, fry from some of these species will be heavily gender biased. Raised for the first few days/weeks of their lives two or three to a small container, then put back together for growout, many hatches are more evenly balanced. This may be due to chemical signals which cause the fixing of gender at some point, or there may be unobserved predation by the slightly stronger fry.
So there may be several things to try if you're getting hatches that are heavily of one gender. Change the pH or the temperature of the water in the breeding tank and/or the hatching and growout containers. Try different pairings of breeders. Or take the extra effort to raise the newly hatched fry for the first few weeks in pairs. You may find an answer that works for you. – G.C.K.A. Newsletter, March 2001 Return to top of page
Another View on … Skewed Sex Ratios
From time to time, those breeding tropical fish encounter a severe imbalance in the male to female ratios of the fry that hatch. A number of theories have been proposed to explain this, including water parameters, temperature, and hormone levels produced by the fish themselves.
Basic to this whole concept is the fact that sex in egg-laying fish is not always determined at conception, but during gestation and within the first month or so after hatching, with outside influences often affecting the result.
"The final sex of fish is determined by environmental conditions," says Wright Huntley, during gestation and early development of the fry.
Experiments on several species of fish have shown that at least in some species, higher temperature or pH levels can affect sex ratios. In the Atlantic silverside (Menida menida) sex determination was influenced by both genotype and temperature during a specific period of larval development (B.E. Kynard). Work by Romer with Apistogramma sp. indicates that higher temperatures usually produced more males, and higher pH more females.
One theory suggests that the presence of male killifish, whether physically or chemically, can inhibit the development of more males, resulting in the majority of the fish becoming female.
A number of killifish breeders have experimented, formally or informally, with adjusting pH, temperature, or rearing practices to influence the sex of fry. In many cases, raising fry in pairs (2 fish per container), often results in actual pairs (one male and one female).
Ron Harlan," says Lowell Patrick, "said that the sex of fry wasn’t determined until around 30 days after hatch, and that the amount of male hormones in the surrounding area influenced the sex of the fry." Working with Rivulus, Lowell tried starting the fry off in pairs in small containers, and went from a sex ratio of 3:75 to 45:55.
"One can improve a terrible sex ratio by limiting the number of fry placed together for the first month of the fishes’ life," Jim Robinson writes, referring specifically to his experiments with Simpsonichthys flavicaudatus Hellner 2. The method does require a great deal of work and a large number of containers, but "for some fish which have a history of skewed sex ratios" it may be the only way to ensure survival of the species.
Obviously, this technique is not for everyone, nor will it work for all species.
"Raising my Rivulus punctatus fry in pairs (they are really hard to get eggs from) has not resulted in an even sex ratio," says Sue Katz. "Females predominate."
However, if you are having problems with a severely skewed sex ratio in a species, it might be worth a try.References: Robinson, Jim. “A Controlled Experiment Concerning Skewed Sex Ratios in Simpsonichthys,” And various other sources.
— G.C.K.A. Newsletter, June 2004 Return to top of page
.Some Observations on Using Peat
"I long ago stopped boiling peat moss," says Robert J. Goldstein. "I keep a big load of peat moss (bulk) plus dead hardwood leaves in a 30-gallon barrel half or more filled with RO water, well aerated to keep it from going anoxic." Over time the peat sinks and the water becomes dark tea-colored and acidic. He uses the peat/leaves in tanks devoted to soil breeders, and uses the water as a blackwater tonic to acidify water for breeding tetras and wild bettas.
"I’ve also used peat moss pellets straight out of the box with the net removed," he reports. "They sink in a couple of days, at most.
"The best tip I’ve learned … for soil breeders was from Robert Nahn, who advised me to use a very thin layer of peat moss in order to not kill the eggs. With a bare scattering of peat moss I now have much higher hatches and can see the eggs easily. I still use deep containers for divers.
"Finally, stick with live foods only in breeding tanks." He also uses Java Moss to take up waste and to provide a refuge.– G.C.K.A. Newsletter, December 2002 Return to top of page
Spawning Media for Annuals –
Some Potential Substitutes for Peat Moss
Aquarists have long depended on peat moss as a water treatment, and killikeepers regularly use it as a spawning medium, particularly for the annual species.
"Nothing else seems to assume [its] many roles," observes Lee Harper. It acidifies and softens water, stimulates spawning, and even helps suppress belly sliders, although evidence indicates that peat extract is as effective in reducing their occurrence. Whether this is due to chemical reactions, or to staining of the water is unknown.
Although peat is nothing like the substrate typical for Nothobranchius habitats, it seems to provide conditions suitable for both the breeding fish and their eggs during incubation, says Brian Watters.
"Peat protects the eggs from predation by hiding them and provides a medium which staves off fungus, to a certain degree," points out William Ruyle.
Most American killikeepers use processed peat, either in the form of "Jiffy Pellets," prepackaged amounts of finely milled peat, or in peat that is baled for the gardening trade. But there are other substrates available which can be used in the aquarium.
Fibrous peat seems to be a European product. North American peat producers don’t seem to make anything quite like it. In Europe, hobbyists collect it from peat producers, where it is an unwanted byproduct of milled agricultural peat. The fibrous material works well either boiled or sunken, or dangling in from the edge, where it replaces spawning mops. It seems to make for a productive "natural" tank, with lots of hiding spaces for eggs and fry and plenty of surface for infusoria. It can also be drained to damp and stored for a couple of weeks to produce "simultaneous hatches" of fry with less size difference.
Bill Gallagher found a substitute spawning medium that many killikeepers have now used with success: ornamental shredded redwood, sometimes called "monkey fur" or "gorilla fur." Used in the landscaping trade, it is sold as ground cover or mulch. It has the same hairy, stringy quality as fibrous peat, and releases a limited amount of humic acid into the water.
"Coconut peat" (coir) can also be used, suggests Tony Terciera, however he recommends that it be diluted with normal sphagnum peat moss. On its own, it may be too coarse and granular, and it lacks the water retention properties of normal peat. He mixes coconut peat 1:3 with regular peat, and when bagging eggs often adds some moist fine peat for incubation. This improves moisture retention and makes certain the eggs contact moist peat particles.
This contact with peat during incubation seems important to successful hatching. "When hatching Nothos I have always ensured that there is at least a half inch layer of peat on the base of the hatching container," says Brian Watters. "If necessary, I place additional peat (preferably old, well soaked or reused peat) in the hatching tray to make up any perceived shortfall. A long time ago I discovered that if you pick out eyed-up eggs … and place them in water without a reasonable amount of peat the eggs will either simply not hatch, or the proportion of belly-sliders will be very high."— G.C.K.A. Newsletter – November 2003 Return to top of page
Spawning Mops … Some Observations
If you breed your tropical fish, you are probably already familiar with spawning mops. These constructions, usually of yarn, provide readily accepted spawning sites and cover for killifish; few killie keepers are without at least a few.Spawning mops consist of two basic parts:
The mop (yarn); and, in some cases
The float
The Mop
Basic mop construction is easy. Simply take a paperback book or similar firm object of appropriate size and wrap the yarn around it as many times as you desire. Tie the loops of yarn tightly together at one end and cut apart at the other to make a “tassel.” In general, thick mops seem more attractive to fish than thinner ones, and darker colors seem to be more readily accepted, but size and color is up to you.
The best yarns for spawning mops are Nylon or Acrylic. They are lightweight, soft, colorfast, and wear well. To condition (or recondition) the mops, place in water and bring to a near boil, either on the stove or in the microwave. This will set any dye residues that may still be in the yarn, and kill any unwanted bacteria, pathogens, or eggs from previous use. Note that overboiling can make some Acrylic yarns tangle and curl into an unusable mass.
Not all mops need to be floated. Some can simply be left to lie loosely on the bottom. Mops can be suspended from suction cops on the side of the tank, or from clips placed over the edge of the tank or attached to tank covers.
If you’re having problems with fungusing eggs, you might want to soak the mop in a Methylene Blue solution. Rinse before using, but don’t be concerned if the water in the spawning tank takes on a blue tint. Meth Blue seems to help keep bacteria populations down, increasing the yield of healthy eggs.
For most species, such simple spawning mops will work quite well. Remember that different species spawn at different levels in the tank, so you may want to make a number of mops of different sizes, including some long ones that reach from the water surface to the tank bottom, to provide a variety of possible spawning sites.
If you are working with fish that prefer to spawn in crevices or tight places, simply fold or loosely “wad” the mop and secure with a rubber band. Alternatively, you can make a “spawning box” using a piece of stitchery plastic canvas (from a hobby store) and two 3″ PVC end caps. Roll the canvas into a tube (tie at the center if it wants to bulge open); stuff with polyester pillow stuffing; put on the end caps and place in an area of active current in the tank.
The Float
For those that want their mops to float, floats can be made from a number of materials.
Wine corks. Simply tie a strand from the mop around the cork.
Styrofoamã . Small pieces of this material can be cut to size, or you can use a couple of “packing peanuts”. Test any “peanuts” before use. Some are now being made of biodegradable material which will disintegrate in water. Styrofoamã may shrink when heated, so be careful when processing.
Plastic film canisters. Just place a strand of the mop’s yarn across the open top and snap on the cover.
Plastic medicine vials. As long as they’ve been washed thoroughly, these work as well as film canisters.
Empty bud tubes. These small vials from the florist are used to hold single flower blooms in water. Simply tape over the open top of the vial, then poke a strand or two of yarn through the soft plastic top that holds the flower stem and snap it in place.
Champagne corks. Make a mop as outlined above, but do not tie off the loops with one knot. Wrap the tie yarn loosely around and beneath the “bulge” on the champagne cork then spread out the loops evenly before tying off.
Swimming pool “noodle.” You may have a couple of these in the house for you (or your kids) to use at the beach. Simply slice crosswise into discs and tie a yarn fringe around the perimeter.
— G.C.K.A. Newsletter, November 2004 Return to top of page
It’s An Individual Thing
Spawning Preferences
We all know that there is a wide variety of possible behaviors when it comes to spawning killifish. Some lay their eggs in plants or top mops, some in the substrate, some in bottom mops, some anywhere at all.
Fundulopanchax gardneri are traditional mop spawners – most of the time. "Here at my place," reports Jim Atchison, "the GAR all tend to choose to spawn in floating mops. But I am finding some of the Mamfense group to be just as likely to spawn in a bottom mop or in peat."
He also finds a great deal of pair specificity in spawning preferences. Some fish like a particular area of the mop, some scatter eggs all over it, some lay eggs in groups, some as singles. Some pairs aren’t productive, but a change in partners can trigger productive spawning. "I don’t think it would be fair to categorize all [fish of a species] ... as being of a particular spawning or behavior type," he says.
"We breed most of the killifish we work with ... in what would essentially be sinking mops. There is a small portion of the mop that may or may not extend from the top of the water, but the vast majority of the mop is lying on the bottom of the spawning setup."
Pair specificity may have a great deal to do with our perceptions of the preferences of particular species. In Jim’s fishroom, three pair of the same species of fish from the same breeder producd, respectively, no eggs at all, 4-5 eggs per week, and 100+ eggs per week. "We have witnessed similar egg production variations many times," Jim says, with no noticeable variables to explain it. "The fish are kept in nearly identical setups and fed the same foods. The water is changed at the same time with the same batch, the mops are made from the same skein of yarn."
If one had acquired the pair that produced no or few eggs, one might consider the fish to be difficult or stingy; while if one had the pair that produced 100+ eggs it might be considered easy.
So you never know.
Remember that "most of what you read is someone’s opinion ... as this is," he concludes.— G.C.K.A. Newsletter, July 2002 Return to top of page
Storing and Hatching Eggs … Alternative Methods
We all know that storing and hatching the eggs of plant-spawners is different than it is for annual killifish, although there are is some crossover.
There are two basic ways most of us handle the eggs from plant-spawners.
1) Spawn pairs in a container or bowl using mops, then a) pick the eggs and incubate in water, or b) remove the adults and let the eggs incubate in the mop.
2) Spawn pairs in a heavily planted tank, then either remove the adults or let the fry fend for themselves.
The disadvantage of both techniques is that the number of fry may be small and/or unpredictable.
If you have fish that you particularly want to reproduce, and the adult pairs are spawning fairly dependably for you, here are two techniques that you might try. Both can result in larger numbers of fry hatched together, which simplifies handling during the growing-out period.The “Baggie” Method
“I pull a mop out of a tank and wring it quite dry,” says Jay-Scott Moylan (don’t worry, this doesn’t crush killie eggs!) He puts the mop in a zip-lock sandwich bag, rolls it up, and labels it with the species, date pulled, etc. Every day for the rest of the week, he pulls the replacement mop from the tank and picks the eggs, putting them into the center of the bagged mop. After a week, the mop with a week’s worth of eggs goes into a shoe box for storage.
“After two weeks,” he says, “I pull out the mops and toss them into plastic shoe boxes with an inch or so of fresh water. Usually the eggs all hatch in a few hours.
“I like having the fry hatch together so they grow at a similar speed.”
The “Foaming” Method
“To some extent oxygen (air) seems to delay hatch in most eggs,” observes Wright Huntley. “As soon as they are dunked in water and the oxygen level drops, they want to hatch if ready.” The “foaming” method is based on this.
“The secret is to keep the air flow going until you are ready for the fry to exit the eggs,” says Charles Harrison. “Start with a 1 or 2-gallon bowl with fresh dechlorinated water. Take one of the mops … and put it on top of an airstone. Now you gotta keep the air going (foaming) for at least three weeks, depending on how many more eggs you add to the mops in the bowl. You can put about half of the volume of the drum bowl full of mop and still have enough air flow and oxygen to keep the eggs from hatching.”
Two weeks after the last egg was added, turn off the air and add about 1/8th tsp. of microworm culture. He has successfully kept many such collected spawns for six weeks before hatching.
“It takes 3-5 hours to hatch every egg in the bowl,” he says.
–G.C.K.A. Newsletter, November 2002 Return to top of page
Storing and Hatching Eggs – Storage on Peat
We all know that storing and hatching the eggs of plant-spawners is different than it is for annual killifish, although there is some crossover. If you have fish that you particularly want to reproduce, and other methods haven’t worked, you might try the peat storage method, which has proven successful when other methods haven’t worked.
"I have had good success with fish that are marginally viable ... by separating the eggs on peat and incubating them that way," says Lee Harper. Others agree. Eggs in peat "are separated so they don’t spread fungus should it develop," Bill Shenefelt confirms, "and the peat (at least for Aphyosemion and Epiplatys) seems to delay development."
"We put all of our eggs ... on peat, and we get much better results than with water incubation," reports teacher Mike Reid, whose students raise killifish as part of their classroom studies. "We … put just a thin layer [of damp peat] on the bottom of a plastic container, add the eggs, put on a lid on it and put it away for a period of time. We check eyes with a magnifying glass to help in determining hatching time. We often miss hatch days and may hatch out several batches spawned over several weeks at the same time. We probably don’t get optimal hatches that way but it does work."
"Put some rather wet peat in a plastic petrie dish or bag," says Wright Huntley. "Put the eggs on peat, over several days, so they are not immersed in water. Seal the container. In 2-3 weeks dunk the whole mess and watch them all hatch in a few hours. Check for eyes (solid gold ring around a black pupil) to tell when they are ready to hatch."– G.C.K.A. Newsletter, December 2002
Problems Breeding Your Fish?
Techniques to Try for Annuals
There are times when no matter what you do your fish won’t breed. Here is how two successful breeders do it.
Allen (Boat) Boatman says that he lets the fish remain together in a "breeding container" (in his case a gallon pickle jar) for one full day. By limiting them to 24 hours, you don’t introduce food that will spoil, and you can monitor the female more closely. When she no longer bulges with eggs, remove the pair. "This is a great method. I have bred Nothobranchius rachovii, N. rubripinnis, N. korthausae "red", N. guntheri, N. kilombero, Fundulopanchax fallax, Simpsonichthys alternatus, and C. nigripinnis this way."
"I have used this [same] method for all Nothos which I do not group spawn," reports John Alegre. Group spawns are 3 or 4 pairs plus a few extra babies in a 10 gal. tank with peat in a freezer container. "When I can’t group spawn, I condition [the breeders] separately and put a pair or trio in a half full 1-1/2 gal. goldfish bowl painted black on the back and sides, with about 1/2 inch of conditioned peat on the bottom." He leaves the fish for 4 days, feeding them about 4 daphnia per fish only on the morning of the third day, then harvests the peat.— G.C.K.A. Newsletter, September 2003 Return to top of page
Those !# Sex Ratios!
A few observations from Dave Koran
Many killikeepers have been frustrated by badly skewed ratios in their hatches, particularly among Nothobranchius and South American annuals.
Many years ago, Steve Sellers pointed out that for him, Canopy. melanotaenia seemed to produce only females "as they got older." Since this species was notorious for killing off females, Dave suspected this might be due to temperature. He had moved from San Francisco to Idaho, where summers were appreciably hotter.
N. furzeri have always been deemed a challenge, yet some breeders are known to keep their breeding areas at 80ºF and never seem to have a sex ratio problem.
In pupfish (specifically Devil’s Hole pupfish in a refugia), the sex ratio was heavily in favor of males when water was in the 80ºF range for a few months. By using a translucent cover to hold in the heat and stretch the warm period by two months, the sex ratio started to even out.
In Sympsonichthys zonatus there is a perceived problem of too many females. When spawned at the mid 60ºF range, they tend to produce a more even sex ratio, or slightly more males. Spawned at 70ºF, the hatches are usually high in females. This same effect can be seen in Cynolebias nigripinnis and C. belottii.
"I don’t believe that this is due to incubation temperature, but rather to the temperature at which the breeders are kept," said Dave.— G.C.K.A. Newsletter – November 2003 Return to top of page
A Trick for Fry Boxes
"The late Steve Sellers had a great way of keeping fry, and I use it with great success," says Robert Rueven.
"Steve put small undergravel filters in all his sweater boxes … with an inch of gravel and some Java Moss." The boxes were "cycled" and he had almost no losses.
Just cut the uplift tube way down and use the undergravel filters made for bowls, 2-1/2 or 5-gallon tanks.
"I pour the fry and peat (for annuals) right into the filtered sweater box." Plant spawners can be placed in such a box after they hatch in a smaller container.— G.C.K.A. Newsletter, December 2001 Return to top of page
Hatching Eggs …
Two Hatch Water Recipes
For those who are having problems hatching their killifish eggs, the following are two recipes suggested by Bill Vannerson. The first is Ed Warner’s tried and true recipe; the second a newer recipe that may also aid in the incubation and hatching of those delicate/stubborn/precious eggs.Ed Warner’s Egg Dye Recipe
1 gallon water 1/2 tsp. non-iodized sal
1 drop Aquari-Sol 5 drops Methlyene Blue
The methelyne blue reduces light; most killie eggs are light sensitive. If the eggs absorb the dye and turn blue, they are either infertile or fungused and should be removed. If you use too much meth blue, all the eggs will turn blue. This dye is not stable, so make up a fresh batch every few days. The Aquari-Sol is an anti-fungal agent; Acriflavine may also be used, but is stronger. Check the containers with eggs daily and dispose of any bad eggs using an eye dropper.
Norm’s Natural Hatching Solution
A gallon jar 12 oak leaves
Rainwater Small fistful of peat moss
Place the peat and leaves in the gallon jar. Fill with rainwater. Let sit until the water turns brown, the shade of Coke. Use as needed for species that like soft, acid water. Replace rainwater in the jar as needed and use until solution loses its brown color, then start a new jug. This method eliminates the need for chemicals and adds tannic acid which inhibits the growth of mold and bacteria. The color reduces light. This “natural” method helps produce large hatches.
— G.C.K.A. Newsletter, January 2003 Return to top of page
Water Flow and Egg Production
Most of us keep killifish in tanks with fairly slow-moving water – bubbling foam or corner filters, slow-running outside filters, under gravel filters. Most of the time our fish do just fine. But what about species that come from moving water habitats, flowing creeks or small burbling streams?
Some species, such as Lamprichthys tanganicus, prefer moving water and seem to thrive in the high water flow and oxygen levels provided by power filters. Some other supposedly "difficult" species, such as Aphyosemion jorgenschelli, A. ocellatum, and A. citripinnis, also come from flowing water habitats.
What do you need if you want to try a high water flow aquarium? Obviously, a longer tank is useful. By placing the water intake and outlet at opposite ends of the tank you can easily create a fairly good water flow. Tank decorations and plants can then provide areas of shelter and slower water, allowing the fish to find their own preferred areas.
A cover on the tank is essential. All fish will jump, and some killifish are notorious for the ability. Completely cover the tank. Glass or plastic covers work well; even window screening will do, as long as it’s tight and you’re careful to plug all holes. Soft foam packing material works well for this; just stuff in small pieces as needed.
Floating plants will discourage jumping, too, although they are a bit messy for some aquarist’s tastes.
There is little scientific evidence to support the idea that for some fish faster flowing water means more egg production, but some have found that making such adjustments has made their fish happier, and resulted in more fry. — G.C.K.A. Newsletter, August 2005 Return to top of page
Water Incubating SJO
Having problems incubating Fundulopanchax sjoestedti? Try water incubation. "In the past 35 years I have raised thousands of SJO using water incubation," reports Al Anderson. "To the water taken from the breeders add 20% sea- water." Remove any white eggs. Keep the eggs in a light proof area at a temperature between 65ºF and 85ºF. "At the warmer temperatures the eggs will start to hatch in about 14 to 18 days. Feed the fry a lot of baby brine shrimp one day after hatching." He notes that fry hatched and kept at a temperature of 70-75ºF will be stronger.— G.C.K.A. Newsletter, May 2003 Return to top of page
Weather Changes, Barometric Pressure, and Breeding Fish …
Recently a number of aquarists have observed what appears to be a correlation between the spawning behaviors of their aquarium fish and changing barometric pressures due to altering weather patterns.
"We had a major storm go through," reports Bob Meyer. "The morning before, I had almost no eggs. Normally I collect about 12 eggs per day per tank. Then the Aphyosemion australe had a major egg laying party. A couple hours later the Fundulopanchax gardneri, and finally right before the storm the Blue Gularis (A. sjoestedti). Every species in the fishroom laid at least twice as many eggs as normal. Something happened, and I [think] it was the storm....
"The fish breed right before or after a rainstorm," Bob says.
The most important stimulus in breeding seems to be barometric pressure.
"Barometric pressures do influence egg production in Aphyosemion species," agrees Tim Addis. "I have found countless times over the years ... [while] collecting eggs daily that there is a pattern of egg production high and low which cannot be explained by temperature, water change, and food. ... The only thing which affects all the tanks ... is barometric pressure."
"Massive water change would induce spawning," Mach Fukada wrote, referring to Rivulus agilae. But "several variables do change with the water change: temperature (usually drops a few degrees), nitrogenous wastes, other mineral concentrations in the water all drop a bit.... I would expect that these factors would all change following a thunderstorm (assuming increased rainfall). I would suspect that these factors all have some influence in the synchronization of reproduction and the suitability of the habitat."
"A series of [weather] changes over a period of a couple of weeks can make some of the elegans group start spawning without water changes," points out Al Anderson.
"I have observed different behavior before a weather change in Aplocheilus lineatus (LIN) and Aphyosemion australe (AUS)," says Gary Harman-Hobbs. "The LIN huddle in the corner in a pretty tight group; usually they would give each other about 3 inches of space. The AUS try to hide under something instead of hanging around mid-water. [And] how do you explain wild fish coming into the shallows or finding deep water before a storm?"
"The angling community recognizes significant changes in gamefish activity that is related to fronts, storms, and presumably barometric pressure effects," points out Lee Harper. It has long been well known by fishermen that changing tides and winds affect fish movement. Frogs have been observed to increase their breeding activity just prior to a storm. But, suggests Lee, "it may be the change and the direction of the change rather than the actual pressure that is the stimulus."
On the other hand ...
"Last year, during the height of the storm season and through a number of major barometric pressure ... [changes] we collected, counted and logged over 8000 eggs from 8 different species of killifish (20 pair)," says Jim Atchison. "The results cast some serious doubts regarding this notion of barometric pressure triggering spawning.
"What we did find was that with little doubt, water changes did have a profound effect on [egg] egg production.... Pressure may be a ‘lead indicator’ of environmental changes to come – fresh water, cooler water, warmer water, food choices." The results of the exercise (and another conducted the year prior) indicate that the three factors responsible for increased egg production were:
1. Feeding live blackworms daily
2. Water changes every fourth day
3. Daily egg harvest (as opposed to weekly)
"We stopped the study on the barometric pressure because results were rather conclusive," Jim said. "Pressure changes had little effect on production of eggs."
"[This] might be due to internal cycles," responds Doug Karpa-Wilson. "It might also be random. It might have to do with changes in light, either total amount or some spectral quality."
So the jury is out. There’s anecdotal evidence, but so far there appears to be no real scientific proof that barometric pressure has a direct effect on egg-laying behaviors among killifish.— G.C.K.A. Newsletter, May 2001 Return to top of page
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