Being small-sized, active, and vibrantly colored, killifish are very popular as aquarium fish. There are around 1270 species of killifish that belong to different families. Among them, the family Rivulidae contains around 320 species. It is said that the name killifish is derived from the Dutch word 'kilde', which indicates their habitat - small water bodies that may disappear during summers. The eggs are laid in the substrate, and hatch only when the dried water bodies are filled again during rains. The fry grow fast, due to the unpredictable nature of their habitat. These fish mate, breed, and die, as the water dries up.
Different types of killifish are raised as pets, and the most popular among them are species from genera like Aphyosemion, Aplocheilus, Epiplatys, Pseudepiplaty, Panchax, etc. You must have a basic understanding about the particular species you choose for your fish tank. If you go for Aphyosemion species, most of them have a lifespan of one year. This is not the case with Panchax species, that may live up to five years. In short, the requirements may vary from one species to another. The following are some general guidelines that can help you in raising killifish as pets.
Tank and Compatibility
These fish can be kept in well planted tanks with slightly acidic water. It is always better to maintain a pH level of 5.5 to 7. They require lower temperature settings and so, they should not be kept with those tropical fish that require warmer waters. You must also provide some driftwood, rocks, etc., that can be used by the fish, as hiding places. Some floating plants can also be added to the tank, which must be provided with a substrate of peat moss. While bigger killifish species can be kept with other fish in a large fish tank, smaller ones often need separate aquariums. It has to be noted that certain species of killifish are very aggressive, especially the males. So, too many males and a small tank is not at all a good combination, as they may fight among themselves and die. They are found to be compatible with small catfish, tetras, barbs, dwarf cichlids, and non territorial fish. It is better to keep them in tanks with secure lids, as they are good jumpers.
Feeding and Breeding
Providing the right food in right quantity is one of the golden rules of killifish care. They can be fed with fruit flies, white worms, mosquito larvae, brine shrimp, grindal worms, etc. You may also use packaged killifish foods that are available in pet stores. Feed the killifish fry with artemia (brine shrimp), for the first week. Later, you may use baby brine and white worms. Regular killifish food can be given, as they grow to adults. As far as breeding is concerned, small-sized fish are found to be difficult to breed. However, you may become successful, if you transfer them to a separate tank and provide the ideal environment. While some species are found to lay eggs on the substrate, others may use spawning mops or plants, for this purpose. Once the fries are born, it will be better to separate the adults. Breeding is said to be easier in lyretail killifish, when compared to other types.
Given above is only a brief and general overview about the subject. It is always advisable to gain a thorough knowledge about the specific type of killifish, you are intending to get for your aquarium.