You’ve acquired your first, new killies. You’re excited about having them. You’ve read up about your new fish, and know what general conditions they prefertemperature, water parameters, and so forthand you have quarantined them for the recommended period of time to assure that they’re healthy.
But you’re wondering: can I introduce these new fish into a community setup, or must I maintain them in a species tank?
Few killi-keepers limit their aquatic hobby only to killifish, and killie tanks are regularly inhabited by other fish, both those that you can find any day in your local aquarium store, or others that are more rarely seen.
The trick to mixing fishwhether in community tanks, or in mixed species tanksis to choose killifish and potential tankmates of similar size, temperament, and needs. A number of popular community species can be successfully mixed with killies, among them: guppies and other small, peaceful livebearers; small tetras, danios, and barbs; dwarf cichlids; and various catfish, particularly the Corydoras.
Michael Reid notes that his daughter has a community tank with male Cynolebias whitei, C. constanciae, and N. guentheri, plus various danios, platys, cory cats, loaches and sharks. All seem to get along quite well, although the killies aren’t quite as bold as the other fish at feeding time. Note that Nothomales are generally intolerant of each otherexcept in large, single sex groups.
Although killies in community setups may spawn, the other fish are likely to prey on the eggs and fry. Some have reported success in spawning and raising killies in tanks with dwarf cichlids. However, Stephen Boulet reports that he has kept Tanganyikan cichlids such as featherfins and dwarfs with Lamprithys tanganicanus, a killie that he says “can fend for itself.”
In addition to the traditional community tanks, a number of successful killi-keepers maintain mixed species killie tanks. Care should be taken, however, to assure that the various species cannot hybridize, and that the resulting eggs and fry can easily be identified.
Good mixes might include an Aphyosemion (mid-water dweller) with a Rivulus and/or an Epiplatys (surface dweller). The fishlook different and have different habits, and the eggs are of different sizesEpiplatys tiny, Aphyosemion medium, and Rivulus jumbo. In addition, such mixes are also often found together in the wild.
— G.C.K.A. Newsletter, August 1997