Killifish

A killifish is any of various tiny, oviparous (egg-laying) cyprinodontiform fish (including families Aplocheilidae, Cyprinodontidae, Fundulidae, Nothobranchiidae, Profundulidae, Rivulidae and Valenciidae). All in all there are some 1270 different species of killifish, the biggest family being Rivulidae, containing more than 320 species. [ [http://filaman.ifm-geomar.de/Nomenclature/NominalSpeciesList.cfm?Family=Rivulidae List of Nominal Species of Rivulidae (Rivulines)] "FishBase". Ed. Ranier Froese and Daniel Pauly. May 2007 version. N.p.: FishBase, 2007.] Although "killifish" is sometimes used as an English equivalent to Cyprinodontidae, some species belonging to that family have their own common names, such as the pupfish and the mummichog. The name "killifish" is derived from the Dutch word "kilde", meaning "small creek", "puddle". Most killies are small fish, from one to two inches (2.5 to 5 cm), with the largest species growing to just under six inches (15 cm).

Range and habitat

Killifish are found mainly in fresh or brackish waters in the Americas, as far south as Argentina and as far north as southern Ontario. There are also species in southern Europe, in much of Africa as far south as KwaZulu-Natal, South Africa, in the Middle East and Asia (as far east as Vietnam), and on several Indian Ocean islands. Killifish are not found in Australia, Antarctica, or northern Europe.

The majority of killifish are found in permanent streams, rivers, and lakes, and live between two and three years. Such killifish are common in the Americas ("Cyprinodon", "Fundulus" and "Rivulus") as well as in Africa and Asia (including "Aphyosemion", "Aplocheilus", "Epiplatys", "Fundulopanchax" and "Lacustricola") and southern Europe ("Aphanius"). Some of these habitats can be rather extreme; the only natural habitat of the Devil's Hole pupfish ("Cyprinodon diabolis") is Devil's Hole: a cavern at least convert|300|ft|m deep, branching out from a small opening at the surface, approximately convert|6|ft|m by convert|18|ft|m wide.

Some specialized forms live in temporary ponds and flood plains, and typically have a much shorter lifespan. Such species, known as "annuals", live no longer than nine months, and are used as models for studies on aging. Examples include the African genus "Nothobranchius" and South American genera ranging from the cold water "Austrolebias" of Argentina and Uruguay to the more tropical "Gnatholebias", "Pterolebias", "Simpsonichthys" and "Terranatos".

Territorial behavior

A small number of species will shoal while most are territorial to varying degrees. Populations can be dense and territories can shift quickly, especially for species of the extreme shallows (a few centimetres of water). Many species exist as passive tribes in small streams where dominant males will defend a territory while allowing females and immature males to pass through the area. In the aquarium, territorial behavior is different for every grouping, and will even vary by individuals. In a large enough aquarium, most species can live in groups as long as there are more than three males.

Diet

Killifish feed primarily on aquatic arthropods such as insect (mosquito) larvae, aquatic crustaceans and worms. It is reported by the killifish collector Rudolf Koubek that areas in Gabon where the streams lack killifish (due to pollution or other causes) are rife with malaria, which is spread by a mosquito. Some species of "Orestias" from Lake Titicaca are planktonic filter feeders. Others, such as "Cynolebias" and "Megalebias" species and "Nothobranchius ocellatus" are predatory and feed mainly on other fish.

Killifish as pets

Many killifish are lavishly coloured; and most species are easy to keep and breed in an aquarium. Specimens can be obtained from specialist societies and associations. Striped panchax (aka. Golden Wonder) are commonly found in pet shops, but caution must be exercised when considering tank mates, since the mouth of the Striped panchax is as wide as the head, and much smaller fish will be eaten.

External links

* Killifish international – [http://www.killifish-international.com Multilingual Killifish-website with a list of breeders]
* killi.net - [http://images.killi.net/ Images of nearly all 700 species]
* [http://www.killiesconnection.org/ Killies Connection]
* [http://www.aka.org American Killifish Association] (AKA)
* [http://www.bka.org.uk British Killifish Association] (BKA)
* [http://www.cka.org/ Canadian Killifish Association] (CKA)
* [http://www.dkg.killi.org Deutsche Killifisch Gemeinschaft]
* [http://www.killifishnederland.nl/ Killifish Nederland] (KFN)
* [http://www.killi.dk/ Scandinavian Killifish Association] (SKS)
* [http://www.elkilliclub.org/indexen.htm El KilliCLUB] (EKC) - internet based, international killifish association
* [http://www.mangrove.org/taylor/ Rare Hermaphroditic Fish Survives in Mangrove Swamps] - D. Scott Taylor, Ph.D - mangrove.org
* [http://www.aik.com/ Italian Killifish Association] - AIK

References

* Costa, Wilson J.E.M. (1998). Phylogeny and Classification of the Cyprinodontiformes (Euteleostei: Atherinomorpha): A Reappraisal. In Malabarba, L. et al. (eds), "Phylogeny and Classification of Neotropical fishes" part 6 (Atherinomorpha), Porto Alegre. 603 p.
* Huber, J. (2004). [http://www.killi-data.org Killi-Data Online]
* Parenti, Lynn R. (1981). A phylogenetic and biogeographical analysis of Cyprinodontiform fishes (Telostei, Alethrinimorpha). "Bulletin of the American Museum of Natural History" 168, article 4.
* [http://news.nationalgeographic.com/news/2007/11/071106-tree-fish.html Fish Lives in Logs, Breathing Air, for Months at a Time] - Aalok Mehta, National Geographic News.