ARK - Arizona Rivulin Keepers

The Maintenance and Breeding of Chromaphyosemions

The following is from the personal website of Olivier Legros. It is offered here with the with the author's permission.

It has been translated using Babel Fish and then edited by Allan Semeit.

The author, Olivier Legros, is a well known killifish hobbyist who has both collected these species and successfully bred them in the aquarium. He shares his techniques in this article.


Adult Chromaphyosemions are maintained in tanks of 14 X 8 X 8 inches (35 X 20 X 20 cm) at a rate of two couples or trios per aquarium. The bottom of the tank is furnished with either Java Moss, fibrous peat or a bottom mop. There is also a green, brown, or blue yarn floating mop. The mop is used more as hiding-place for the fish rather than egg-laying substrate. Black paperboard darkens the small back side of the tank, as well as the bottom. The aquarium receives only daylight (window in north), except the evening when it is lit for a few hours (all depends on the season) by bulbs of 15 Watts (two for four tanks).

No filter is used. Only a light aeration is used in order to avoid the formation of a bacterial film on the surface of water. Every fifteen days, a third of the volume of the tank is replaced. If this change is not done, the water becomes too acid and the eggs are not fertilized any more or burst between the fingers.

Rainwater is combined with water of the tap. This is done to avoid a pH crash after a few weeks. This mixture has the following characteristics: pH 7; DH 8; T° 22-23°C.

Chromaphyosemions are generally peaceful. It is thus possible to maintain several pairs in a same tank. One should not keep together more than three males. This is not because there could be danger to their lives but because when too many males are kept together they tend to fight more frequently and damage their fins. These engagements are pronounced mainly right after water changes.

Bloodworms constitute the principal food for my adults. When bloodworms are unavailable then daphnia and frozen worms replace them. Only the least timid populations will come to the surface and feed upon fruit flies.


Generally speaking, breeding Chromaphyosemions is not a challenge. Certain populations can be an exception. On the other hand, there can be a challenge with your obtaining very unbalanced sex ratios, in particular with C. riggenbachi and certain C. splendopleure. This may necessitate breeding your fish several times in a year in order to obtain a better balance. Natural reproduction is observed regularly, but generally in the adults at least one year old. It is necessary to acknowledge that Chromaphyosemions are not very productive and do not always produce enough offspring to ensure the maintenance of the species.

Collecting the eggs is done in the maintenance tank. A trio is normally more productive than several trios placed in the same tank. By maintaining separate trios, I simultaneously collect eggs of the same species in two different tanks. This improves the genetic diversity. For the same reason, I often get additional breeders from other aquarists.

Spawning fish prefer the following breeding materials, in order: fibrous peat (but I prefer the bottom mop as it is cleaner and the eggs are more easily collected), Java Moss, and a floating mop. The eggs are collected and incubated in the water of the breeders, hatching in two to three weeks depending upon the temperature. An addition of a light coloring of acriflavine is desirable to avoid the fungus. Water is changed daily when the inspecting the eggs. Bad eggs are removed. Sometimes with C. loennbergii and C. riggenbachi, certain eggs hatch only after more than one month, undergoing, seems, a kind of diapause.

Another lazy " method " of breeding is to just transfer the breeding material to another container. This is has proven less productive than the collecting of eggs. Also "dry" incubation has never given me of good results. The eggs become dehydrated, mildew attacks them, or the fry hatch before you add water to the peat moss.

The Chromaphyosemion varieties and populations that have produced well for me have been: C. bivittatum Fungé, C. bitaeniatum Lagos, C. riggenbachi Somakak and Yabassi, and C. poliaki Bolifamba.

Raising Fry

The fry, as soon as they hatch, are transferred in small plastic containers. They are fed infusoria, microworms, and baby brine shrimp. These three foods are almost essential to succeed with newborn C. bivittatum, C. splendopleure, and C. bitaeniatum. The other species can be fed upon hatching with vitamin-enriched nauplii of baby brine shrimp. Again, make small water changes daily.

After a week, the fry are placed in a tank identical to that of the adults, but with coarse peat. Water will be made more alkaline by adding tap water. This thwarts the acidifying effect of the peat. Salt is never added, except at the time of an attack of oodinium. The depth of water, only a few centimeters at the beginning, can be increased according to the growth of the young fish. Do this one drop by drop very slowly (I insist there). Adding new water too quickly often seems to contribute to a bloom of oodinium. After sexual maturity, your water can be made more acid and less hard by adding rainwater and using coarse peat.

The growth of the fry is very slow and varies from one population to another. After around two months the two longitudinal bands (or lines) on the sides appear (except for C. riggenbachi ). One can recognize the first males thanks to the orange or bluish reflections in the anal fin after around 2 1/2 - 3 months. At around five or six months, the fish may start to lay eggs, but it is only after one year to one year and half that your males will obtain well developed fins.

The Chromaphyosemion females have a very similar appearance. If you cannot maintain a population species separate from others of this kind, it is very difficult to determine which female belongs to which population (but possible, to see in appendix). It is very important not to mix the different populations. Having your tanks in a row, you may happen to accidentally mix populations. It sometimes happens to me. Do not hesitate to eliminate them, particularly if they are fry or females. It is by these precautions that you will manage to preserve your pure strains.


Chromaphyosemions are not very sensitive to diseases and can live between two years and two years and half. In fact the females have greatest longevity.

Only one disease is current in the adults: oodinium (also known as Velvet). Generally, an outbreak is easily stopped by the addition of two spoons with cooking salt soup for 15 liters. If the subjects are powdered with white points and the salt addition is not enough, bathe the adults for a few minutes in a copper sulfate solution to 1% (some drops of CuSO4 with 1% in 200 ml) and this will eradicate this plague. Reasons that may cause an outbreak of oodinium include: adding new water too quickly, having aquarium water become too acid, overcrowding...

This disease can cause true devastation to your fry. You need to be vigilant. For fry, only salt is effective, the copper sulfate can be fatal.