Mosquitofish (Gambusia affinis) are an integral part of the District’s mosquito control program and are a type of biological control to eliminate immature mosquitoes before they reach adulthood. This type of control method can be highly effective due to the predatory behavior of mosquitofish on mosquitoes in the larval and pupal stages.

Mosquitofish are not native to California. District technicians distribute thousands of fish each year to water sources that do not connect or drain to natural water bodies such as creeks or rivers. Sources in which mosquitofish are planted include but are not limited to, neglected swimming pools and spas, ornamental ponds, water troughs, and flood control basins. Mosquitofish are able to withstand a fairly harsh aquatic habitat, such as polluted water bodies with limited food resources.

Mosquitofish Facts

• Mosquitofish are small fish with the female being no more than 2 inches and males being no more than 1.5 inches.
• One mosquitofish can eat 49-65 larvae in a half-hour period.
• The lifespan of a mosquitofish is approximately 2 years and is dependent on the environment and food availability.
• Mosquitofish are ovoviviparous, which means that they give birth to live young and do not lay eggs.
• Mosquitofish feed on mosquito larvae and pupae.
• Their diet is not limited to mosquito larvae and pupae. They will also feed on invertebrates and algae.
• They are aggressive feeders and have been known to eat their own young.

Residents that live within the District can request mosquitofish. Please visit our web map to determine if you live within District boundaries before making a fish request.