It is against California Department of Fish and Game regulations for private citizens to plant mosquitofish in waters of the state without a permit.

About Mosquitofish

Mosquitofish are the most used biological control agent in the world. They are great at protecting your home from mosquitoes because they feed on larvae. To be effective in preventing mosquitoes, the use of mosquitofish should be paired with a weekly habit of removing stagnant water sources around the home.

The District provides FREE mosquitofish to District residents for placement on their property only. A service request must first be made to determine if mosquitofish are the appropriate method to control mosquito larvae. Placement must be made by a technician.

These fish are routinely stocked by Vector Control Specialists to control mosquito populations in sources such as artificial lakes, irrigation ditches, and industrial ponds. By law, Vector Control Specialists can place fish in water sources other than those located on private property. To avoid competition with sensitive native amphibians and fish species, we do not stock mosquitofish in habitats where such species are known to be present.

Mosquitofish (Gambusia affinis) were first introduced to California in 1922 for mosquito control. Instead of using insecticides to control mosquitoes, fish are an attractive and effective alternative. This method is referred to as biological control and is part of the Integrated Vector Management (IVM) Program at the District.

Advantages of Using Mosquitofish Over Other Fish in Water Sources

• Gambusia are specific to consuming mosquito larvae. This is due to their upturned mouths naturally adapted for this purpose.
• Small, which enables them to inhabit shallow waters and penetrate dense vegetation growth where larvae and pupae hide.
• Broad tolerance to a wide range of environmental conditions, such as temperature changes, salinity, organic pollution, and poor food supply.
• Relative lack of disease.
• Easily maintained.