I am a well known breeder of rare, strange, unusual, and otherise oddball fish. A good percentage of my fish collection is killifish. I have annual killifish, non annual killifish and semi-annual killifish. I have the basic killies that we all know and love and I also have obscure killies such as pupfish and lampeyes. My killifish collection ranges from very common to very rare, from the beginner's easy to the expert's difficult. Though killifish are not the only fish I hav eor love, they are a very important part of my fishroom, my hobby, and my business.

Many new and intermediate hobbyists look to me for advice. People that are just beginning often have the same questions again and again and one of the most common and important questions they ask is "can I keep killifish in a community tank?".

The short answer is yes. There are many misconceptions about killifish and there are a lot of breeder's who want to keep it this way. Not me. I hope to clear up the community tank issue on this article. And if any of the readers have any questions, feel free to contact me.

Some people say you cannot keep killifish in a community tank and this is absolutely not true. Now there are certain species that I would not recommend for a community tank, but the beginner killifish enthusiast is not going to be dealing with these species anyway. The vast vast majority of killifish CAN be kept happily and healthfully in a community tank of small and peaceful fish.

Before you go forward with purchasing fish, you will need to know a little bit about the fish themselves.

Killifish are found on every continent in the world except for Australia. They are from the same family as livebearers; the toothcarps. Livebearers are the livebearing toothcarps and killifish are the egg laying toothcarps. Killifish are often referred to as "Rivulins" or "panchax" but this is becomming less and less common, as it is the old way.

Killifish are separated into 2 main categories: annual and non-annual. 

An annual killifish is the kind who's eggs dry out in peat moss. These fishes natural habitats dry out each year, which causes the early death of the fish. The eggs remain in the dried habitat until the next year's rains when they will hatch. In aquariums we replicate this proccess by removing the eggs from the tanks and drying them for extended periods. In their natural habitats these annual species have very short lifespans of only a few months, but in an aquarium they can live up to 2 years.  Due to the short natural lifespan annual killifish have an extremely fast growth rate, perhaps the fastest of any fish.

A non-annual killifish is a killie who's natural habitat does not dry out. These fishes eggs incubate in water and for a much shorter period of time. These fish have longer lifespans and they grow much slower than their annual cousins. Exact lifespan and growth rate depends onthe species and many environmental conditions.

There is also a third category of killifish known as semi-annuals. These fishes natural habitats sometimes or partially dry out. For breeding purposes all semi-annuals can be grouped either as annual or as non-annual, depending on which way it's eggs incubate more successfully. Those who's eggs incubate better in water are bred like non-annuals and those who's eggs incubate better dry are bred in the same fashion as annuals.

For keeping killifish in the community tank for their beauty it does not really matter whether the fish is annual or non-annual. Both annuals and non annuals can be successfully kept in the right community tank.

However if you have the desire to breed them in your community tank you will want to choose a non-annual species. Because annuals lay their eggs into peat moss they must be housed ina  bare bottom tank. Annuals cannot be bred successfully in a community tank that contains a gravel substrate. Non-annual species breed in spawning mops and can breed successfully in the right community tank.

If you plan to breed your non-annuals in your community tank you will need a bowl to hatch the eggs in and a fry net to raise the fry.

Now there is no guarantee that your killies will breed in the community tank anyway. They can be touchy. But if everything is right..... the tank is not stocked too heavily, tankmates are small and peacefull, and the fish get enough to eat, then there is a very good chance they will. They do not require environmental cues to induce spawning and they lay their eggs on a daily basis.

Another beginner's misconception is that killifish can only be kept in pairs. That is not true at all. The majority of killifish breeders breed their fish in colonies consiting of several pairs or a few males and multiple females. However it is good advice to give them some room because males do bicker a bit. This is less of an issue if the males were raised together.

If you are keeping killifish just for their beauty and you have no intention to breed them, you can mix almost any species you wish. But if you want to breed them you will need to avoid hybridization by not keeping 2 species of the same genus together. What I am saying is that you can keep an Aphyosemion species with an Epiplatys species, but don't mix 2 Aphyosemion species. Same goes for killies of all genuses.

While most breeders choose not to keep their killies in community tanks, it certainly can be done and there is no reason why you shouldn't. In fact it is probably a good idea to try out killies in your community aquarium and see if killifish are for you before you go out and spend a bunch of money on multiple tanks. Killifish aren't for everybody but those who like them often become very serious about what they are doing. Good luck and happy fishing : )