FAQ – General Killifish Questions

Questions about killifish

What are killifish and why are they called that?
 Scientists have defined Cyprinodonts as carp-like fish with teeth. Those are further split between livebearers, like the common guppy, and those who lay eggs. The egg-layers were called Panchax and Killifish by various folks, but the founders of the AKA decided to use killifish as the general name for the egg-laying toothed carps. It seems to have stuck.

“Kill” is an old Dutch word for stream or brook that appears in many geographical names, like Catskills, Peekskill, etc. Since most of these fish are tiny and often live in smaller waters, the “fish of the stream” seemed like a good name for them.

Where do killifish live?
 Killifish are opportunists and very tough, so they have populated small waters all over the earth, except in Antarctica (too cold for fresh-water fishes) and Australia (where other species already filled those environments).

A great many species ended up on coastal shelf areas. They may live in brackish waters and even in the open sea. Those range from excellent aquarium fish, like Jordanella floridae, the American-Flagfish, to many you will never see in an aquarium store. Generally, the coastal species are the only killifish that have a widespread geographical distribution. Most are restricted to very tiny habitats, which tends to make them vulnerable to changes in habitat brought about by development.

The Cottonball-Marsh Pupfish, Cyprinodon milleri, lives below sea level, in Death Valley, California, in water that can be 104 degrees F, and salinity nearly 5 times higher than sea water. Other killifish, known as annuals, live in temporary waters that may dry up every year. Their eggs are placed in the mud, and hatch when the new rainy season starts. These “instant fish” are a fun part of the hobby. Killifish seem to invade any water that provides some food and some protection from predators.

Are there any good books on killifish?
The AKA provides an excellent Beginners Guide when you join the AKA. This book can also be purchased from the Online Store.

The late Ed Warner’s book, Success With Killifish, a 48 page paperback with a few color pictures, is an excellent complement to the Beginner’s Guide. Copies may available from Ruth Warner and often show up on auction sites.

Another excellent paperback that is inexpensive is by a real killifish fanatic, Steffen Hellner, the Barron’s Books Killifish: A Complete Pet Owner’s Manual. Both of these paperbacks are a bit dated, as far as fish names go, but the basic information there is very good indeed. Pictures are outstanding. Both are out of print, but often still available for $10 or less. Check your pet shop shelf or online auctions for this one.

When Steffen Hellner joined the folks that produce the Baensch and Riehl Aquarium Atlas series, he greatly expanded the killifish descriptions and coverage, particularly in Volume 3. Volumes 1 and 3 are worth owning for the killifish descriptions and pictures, alone. With 118 pages of killies, Vol. 2 actually is pretty decent, too.

The AKA Online store carries several other books on killifish. These often focus on specific groups and may appeal more to the specialist.

The World of Killifish series also available from the online store is also called the “Wildekamp” series by hobbyists. They contain no color photos, but do have accurate line drawings and much useful information on each species covered. Published by the AKA as a service to the hobby, it is a work in progress. Four of five planned volumes have been published.

How many kinds of killifish are there?
 Scientists have described over 800 species, and new ones are being discovered all the time. It is even possible that there are over 1000 killifish species on earth, right now. Names can change as scientists study the fish, which can be confusing for us all.

The AKA has published a list of officially-approved species names, known as the Killifish Master Index (KMI), by Dr. Ken Lazara. The KMI 4th edition as well as other excellent references are available in the online store. Killidata is a useful online reference work, maintained by Prof. Jean Huber.

By standardizing on KMI4 for fish names, we reduce confusion at local club sales and in the Fish and Egg listings in the AKA Business Newsletter.

With so many scientifically-named species, and so little distribution through normal commercial fish shops, it is not surprising that most killifish don’t have common names. Folks new to killifish are often intimidated by the Latin names and the collection codes or location names used to prevent accidental hybridization. It takes a bit of getting used to, but works best for the hobby in the long run.

What is needed to keep killifish?
 They are mostly tropical fish, that may need a bit cooler water than other tropicals, but usually warmer than goldfish. Lots more information is available in the on-line extracts from the Beginners Manual in this section of the site.

What kind should I start with, and where can I get them?
The Beginners Guide gives more detail, but your local tap water is an excellent guide. If it is hard water, you may do better with Fundulopanchax and Nothobranchius species, but Chromaphyosemions and many other Aphyosemions may be happier if your water is quite soft.

Killifish are most easily acquired at AKA events or at AKA Affiliate Club Meetings.  Local Aquarium Society meetings and auctions are also often good places to find killies. Although many killies are available from online auctions, you are more likely to have success with killies if you can find a local killifish keeper who is willing to help you learn what is involved to successfully keep and breed killies.

Choose a species that is relatively straightforward to breed. It is useful to ask at local affiliate club meetings or look in the AKA Forums about choices.

Why can’t I get them at my Local Fish Store?
 You will not find many killies in shops, as they have never been easy for the commercial suppliers to mass produce.   Most killies are either bred by small breeders at home or wild caught.  Because the males of most species fight, shipping wild-caught killies is expensive.  Expect to pay $25 to $50 per pair IF a fish store carries them.  Additionally, most killies are excellent jumpers so if a store employee does not keep the tank tightly covered, lots of expensive stock ends up on the floor.

Many hobbyists breed killies which are distributed within the killifish world.  Although many killies are easy to breed, they are difficult to produce in large numbers.  Killies are generally not good community aquarium residents.  Although not difficult to keep, they do require special considerations and many killie breeders find it offensive when newbies toss them in a community tank and they end up dead on the floor the next day.

Contact your closest local affiliate club and attend a meeting to get good starting stock or purchase from the AKA Fish and Egg listing, which is updated monthly.

Many store owners think killifish are short-lived, because they have heard of the “annuals” that can grow, reproduce and die in a single rainy season. The fish actually live about as long as Rasboras and many Tetras, and even some annuals can live for two or more years.

Many killies are so easy to breed and raise in small containers that hobbyists tend to freely share them and inadvertently interfere with the normal commercial trade in tropical fish. We should bend over backwards to support our local shops by buying foods, hardware and other such supplies there when possible.

I heard they need live foods. Is this true, and where can I get such food.
 Being “toothed” carps is a clue. They tend to be eaters of live stuff, so some live food in their diet is a good idea. Many fish stores sell live brine shrimp and California black worms (sometimes called “tubifex” or blood worms which are actually different worms). True Tubifex worms are illegal in some states, but available in others, and excellent food if properly stored and purged of wastes.

Some killifish also require a lot of vegetables in their diet. These include pupfish and springfish as well as many of their livebearer cousins. Blanched zucchini ends are often devoured eagerly.

Most serious killifish keepers learn to hatch baby brine shrimp. These serve as great conditioning food for getting breeders to make healthy eggs, and are nearly essential for raising baby killifish.

Hobbyists also exchange other live-food cultures that can be kept in the fish room or refrigerator.  See the Beginner’s Manual for details.

The presence of West-Nile Virus, Eastern Equine Encephalitis and other mosquito-borne diseases has brought into question the old habit of raising mosquito larvae for our killifish. They are among the finest foods known, but our neighbors and officials may not approve. Likewise midge-fly larvae (bloodworms) and glass worms are good foods for adult fish. Available as freeze-dried, most killifish will eat the dried products when rehydrated. Frozen foods are also a good substitute for live foods for many species.

Some killifish also will eat high quality flake food, but make sure you buy a brand that is high quality. If you use a cheap brand the fish may not eat it and it will end up fouling their water.

Where do I go for help?

The place to go to ask questions is the forums on this site. There is a Beginners Corner, if you feel you fit into that category, a General Killie Discussion forum, and several other more specialized ones. Killifish hobbyists are among the most generous at sharing their expertise. To avoid repetition, try searching the site for an answer before posting your question. One motive for doing this FAQ was to avoid the same questions being asked and answered there, time and again.

If your question reveals that you have searched those places, it is more likely to get a good, thoughtful answer by a member.

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