All fish / Poeciliidae

Western Mosquitofish

Gambusia affinis

Also known as mosquitofish, mosquito fish, western mosquito fish, gambusia, mosquito eater, topminnow, ปลากินยุง, ikan gambusia, カダヤシ, 食蚊鱼, 大肚鱼

A small, plain olive-grey livebearer with a flat head and upturned mouth, with females growing noticeably larger than the slim males. It is extremely hardy and tolerates a wide range of temperatures and water conditions, so it is mostly kept in ponds and water butts for mosquito control or by native fish enthusiasts.

Care at a glance

Care level

Easy

Temperament

Semi

Adult size

4 cm

Temperature

12 to 30 °C

pH

6.5 to 8.5

Smallest tank

60 litres

Keep as

Group of 6 or more, with more females than males

Diet

Omnivore: flake, small live or frozen foods such as mosquito larvae and daphnia, plus some plant matter

Swims

Top of the tank

Lifespan

1 to 3 years

Water

Freshwater

Wild range

Southern USA and northeastern Mexico (Mississippi basin and Gulf Coast drainages)

Breeding

Livebearer; females give birth to batches of fry every few weeks in warm months after internal fertilisation. Breeding is very easy, but adults eat their young, so dense plants help fry survive.

Good to know

It nips fins and harasses slow or long-finned fish, and is listed as a damaging invasive species in many countries, including the EU and Australia, where keeping or releasing it may be illegal. It is easily confused with the closely related Eastern Mosquitofish, Gambusia holbrooki.