Disease Control
By Jim Langan

This is one of the most important tasks of raising quality healthy fish, however, it is probably the least understood task by most kill keepers.  Most of my experience in Killie keeping has been with Aphyosemion and Fundulopanchax genera killies, I have not raised many Nothobranchius or Epiplatys genera and the treatments opinions and practices of this article are limited to Aphyosemions and Fundulopanchax genera species.

I've visited many a fish room over the past 10+ years in killifish keeping.  Every killie keeper has a variance of opinions on disease control.  Some killie keepers don't do any treatment of diseases while others are very invasive.In my opinion disease control not only covers disease prevention but includes intervention when diseases are discovered.  First I will begin by defining a killifish disease.  The definition which I use is "an impairment or ailment  which physically disrupts the natural development, deportment or appearance of the subject". Diseases occur from a variety of sources some such sources are: severe pH water changes, severe water temperature changes, water pollution, improper feeding and fish incompatibility.
Fish diseases from sudden water temperature changes are instantaneous.  My only experiences with this problem were in my novice days [30+ years ago] when I would perform 100% water changes by removing my goldfish from one bowl of water and placing it in another.  I quickly learned that, if the water temperature difference  was too great the fish started swirling on its side and soon was headed for the toilet.  Very rarely does this problem ever occur with experienced killie keepers and I will not further discuss this scenario.

Fish diseases from mild and severe pH changes are more common and unfortunately happen more frequently than we are aware.  Question: Have you ever transferred fry from small trays or cups into a larger tank, and then lost most or all of batch in a few days? Or Have you ever changed water in a tray or cup and lost most of a healthy batch of fry in a few days?  Or Have you ever performed a water change or moved fry to another tank and suddenly end up with "belly sliders" from apparently healthy fry?  I don't know about you but this event happens to me more often than I would like.  At first I thought this was due to temperature differences, however, I use a calibrated digital thermometer and I have ruled out temperature as a possibility. A more plausible cause is that fry are more sensitive to pH changes than adult fish.  They simply have less body mass and consequently less resistance to environmental changes.  I typically use reverse osmosis filtered water for hatching my fry pH of about 6.8 aged two weeks and at room temperature.    I use pH test kits to monitor my water.  I raise my fish in tanks which contain water of pH 7.2-7.4.  This water is derived from pure RO water and Madison tap water which has a pH of approximately 8.4 [I call it liquid rock]. 

Whenever, I have lost large amounts of fry from a transfer I carefully examine them [the dead ones] with a microscope.  In almost all cases I have observed serious infections of Oodinium or most of us know this as "velvet".  Velvet is a parasite which exists in most room temperature fish tanks.  I have usually found that a lower fish resistance due to relocation from pH changes triggers the velvet infections.  If diagnosed early velvet is easily treated with Acriflavin, Methylene Blue, Copper Sulfate, and in mild infections table salt.  Don't use table salt on Rolloffia type Aphyosemions they will not tolerate it.  In small fry by the time velvet is observed they fry are usually too far gone to survive even the most aggressive treatments.It is far better to understand the mechanism which causes the velvet outbreak in killie fry.  When fry are raised in small trays or cups during their first few  weeks of life water changes are usually not performed.  Thus, effluent matter builds up from excretions of the fry and excess food.  As this matter decays the pH drops in the water.  This happens over a long slow process and the fry are relatively unaffected by the low pH.  I have measured pH as low as 5.0-5.4 in my fry containers after three weeks.  When these fry are moved into a pH of 7.0 - 7.4 they adapt to the pH without showing problems of deportment, however, their resistance to infection is altered, yielding a velvet infection.  Result, death after 4-5 days.After realizing the actual cause of the velvet infections, I now add water of pH 7.0 to my fry containers several days before I transfer them to larger quarters.  Consequently, I now have significantly less losses of transferred fry.  Although this problem occurs with Aphyosemions it occurs more often in Fundulopanchax genera.  The reason is simple,  many Fp species are hatched from peat.  The peat adds a lot of acidity to the water's chemistry.  Since you are starting out with a lower pH usually around 6.5 or lower it takes less decaying matter to significantly lower the fry containers pH.  It has usually been the Fp. Species which reach the low 5.0s in pH in my fry trays and cups.

Adult Killifish infections caused by poor water conditions are usually bacterial.  Bacterial infections usually are secondary.  The fish has most likely been injured by another fish or from a parasite.  Bacterial infections are most likely observed around the mouth, gill plates, body, and fins.  These Infections typically appear as white cottony patches.  These patches are caused from fish's mucus and bacterial residue.  Many novice fish keepers associate this type of infection as a fungal infection and treat accordingly.  Consequently the bacteria flourishes and the fish soon die.  True fungal infections are virtually non-existent in killies and 99/100 fungal infections are really bacterial ones. Most of these types of infections are gram-positive bacteria.  MARACYN works extremely well.  I usually isolate the infected fish into a small 2-1/2 gallon tank and treat per instructions.  I will also perform a 50% water change on the tank from which the infected fish was isolated.  This will significantly reduce the chances of the remaining fish catching the bacterial infection. In cases were treating with MARACYN isn't effective, or the fish has fin infections I will use MARACYN-II.  MARACYN -II is specifically designed to treat gram-negative bacterial infections.  Typically gram-negative infections do not have white cottony patches on the fins.  This type of bacterial eats the soft tissue of the fins until only the fins rays are remaining.  After that the bacteria infects the rays roots and the fish will begin to hemorrhage at the fins base.  Once hemorrhaging begins  the fish has only days to live.  Again isolate the fish and treat with MARACYN-II.  Perform water changes on the tank of which the infected fish was removed.  This type of infection is usually caused by extremely poor water conditions and neglect.  Any remaining fish should be watched closely and often for fin bacteria.  This type of bacterial infection is usually not due to an external injury, and it is contagious.

Parasitic infections can be caused from a number of circumstances which range from poor water conditions, contaminated food, introduction of "new" already infected fish.  Poor water conditions are easily controlled and prevented.  Don't procrastinate on those water changes.  If you have too many tanks to clean, cut back some.  Don't make your fish suffer from your mistakes.  When feeding live food such as tubifex, black worms and glass worms rinse them out, keep them in the refrigerator the cold temperatures will prevent the parasites from reproducing and in some cases will kill them.  Quarantine your new fish for at least two weeks prior to their introduction into your breeding tanks.  External parasites are easily treated with Acriflavin, Methylene Blue and Copper Sulfate. Severe thinning of the fishes "gut" or main body, or partial or total loss of appetite this is usually caused by intestinal parasites, round worms, intestinal flukes etc…  I've found that levamisole is extremely affective. After answering a lot of detailed questions, you can obtain levamisole from your local veterinarian.  Levamisole is a readily available cattle de-wormer.  This medication is found in both pill and  solution.  I use the pill form because the solution has a very limited shelf life.  First you will need to grind up the pills and dissolve them in water and the mixed solution to the tanks water. Levamisole Hydrochloride comes in 50 gram packages.  When this powder is mixed with 3 ounces of water a 5% solution results.  Use 30 drops of solution per 2 gallons of water.  Levamisole Sulfate comes as a 13% solution, use 15 drops of solution per 2 gallons of water.  The calculation for the dry powder treatment dosage was described in the March/April 1998 Journal of The American Killifish Association, Title "A Treatment for Camallanus", written by  Charles Harrison.  The calculations for the Levamisole Sulfate solution  was derived and tested by me. I always remove any filtration so that the parasites can't "hide" and re-infect the fish after treatment stops.  Instead of filtration I aerate my tanks with an airstone.  Perform water changes daily and always add  fresh levamisole with each water change.  This treatment is usually affective after three to four days.

Parasites such as gill flukes and body flukes are often observed with the naked eye.  On large adult fish this is mostly an annoyance, however, small fish can be seriously effected.  Many affective over the counter treatments are available from pet stores.   Isolate the fish and treat as recommended by the manufacturer.  Keep fish isolated after treatment for at least one week.  During this time carefully and routinely observe the fish for secondary bacterial infections which are often residual after parasitic infections. Internal bacterial infections can occur as a secondary problem after the treatment of gill flukes, intestinal parasites and velvet.  These are typically gram-positive bacteria and are treated with MARACYN. I do not use tetracycline or sulfa based medications to treat bacterial fish infections.  My experience with these medications have usually resulted in dead fish because of their chemical base, causing extreme, sudden pH changes.

Although many medications are available to the aquarium hobbyist, the medications which I stock are : Acriflavin, MARACYN, MARACYN-II, Levamisole, Methylene Blue, Malachite Green, Formalin,  Copper Sulfate, and rock salt.