Mosquito Control & Other Vectors
Biological Control

Biological mosquito control methods are one of the mainstays in protecting the public from mosquitoes and the transmission of mosquito-borne diseases. Mosquito biological control agents include a wide variety of pathogens, parasites and predators. The primary biological control agent used by the District is Gambusia affinis, the mosquitofish.

Mosquitofishes held in palm of hands

Mosquitofish are small live-bearing minnows closely related to the common guppy. Used in mosquito control in California since 1922, these fish are vivacious consumers of mosquito larvae and pupae and can survive in varying water conditions. Because mosquitofish are surface feeders, they are extremely efficient mosquito predators. Mosquitofish have been said to consume upwards of 80-100 mosquito larvae per day, and are capable of quickly populating a source if conditions are favorable. The fish are placed in a variety of permanent and semi-permanent fresh water habitats, including dirty swimming pools, water troughs, rice fields, and wetlands.

Mosquitofish are reared at the District's White Slough Mosquitofish Rearing Facility, where several thousand pounds of fish are produced each year. Additionally, mosquitofish are harvested from sites where they were introduced earlier, providing for supplemental rearing and storage sites.

San Joaquin County residents can receive mosquitofish free by calling the District, by filling out the request service form, or by picking them up at 7759 S. Airport Way, Stockton, CA.