Mosquitofish

The western mosquitofish (Gambusia affinis) is a species of freshwater fish, also known commonly, if ambiguously, as simply mosquitofish or by its generic name, Gambusia, or by the common name gambezi. There is also an eastern mosquitofish (G. holbrooki).

Mosquitofish are small in comparison to many other freshwater fish, with females reaching an overall length of 7 cm (2.8 in) and males at a length of 4 cm (1.6 in). The female can be distinguished from the male by her larger size and a gravid spot at the posterior of her abdomen. The name "mosquitofish" was given because the diet of this fish sometimes consists of large numbers of mosquito larvae, relative to body size. Gambusia typically eat zooplankton, beetles, mayflies, caddisflies, mites, and other invertebrates; mosquito larvae make up only a small portion of their diet.

Mosquitofish were introduced directly into ecosystems in many parts of the world as a biocontrol to lower mosquito populations which in turn negatively affected many other species in each distinct bioregion. Mosquitofish in Australia are classified as a noxious pest and may have exacerbated the mosquito problem in many areas by outcompeting native invertebrate predators of mosquito larvae. Several counties in California distribute mosquitofish at no charge to residents with manmade fish ponds and pools as part of their mosquito abatement programs. The fish are made available to residents only and are intended to be used solely on their own property, not introduced into natural habitat. On 24 February 2014, Chennai Corporation in India introduced western mosquitofish in 660 ponds to control the mosquito population in freshwater bodies.