Mosquitofish (Gambusia affinis) are live bearing freshwater minnows related to guppies. These small fish (1-2 inches in length) are top swimmers that feed on insects and wind-blown organic debris at the surface of the water. They have a voracious appetite. An adult can eat hundreds of mosquito larvae a day! This makes them an excellent biological tool for mosquito control, as the fish gobble up the mosquito larvae before they have a chance to develop into flying, biting adult mosquitoes.


Biological Control

As a natural predator of mosquito larvae, mosquitofish have been used for mosquito control purposes throughout the world for many years. More than 100,000 of this fish are produced each year at the District's mosquitofish production facility. READ MORE.


image Mosquitofish Care

Detailed information regarding the proper care of mosquitofish. READ MORE.


image How to Get Mosquitofish

PLEASE NOTE: In-person mosquitofish pick up is temporarily discontinued. Please make requests for mosquitofish through the District voicemail at 925-685-9301 or online. Once a request has been made, a District employee will inspect the property and if mosquitofish are necessary and appropriate, the employee will place the mosquitofish in the Contra Costa County water feature associated with the request. 


imageMosquitofish Research Videos

These videos are dedicated to the biological element of our Integrated Vector Management Program - using mosquitofish and researching the potential species of other fish to help combat mosquito larvae naturally. READ MORE.


image Fisheries Research Documents

Documentation of researching the potential for utilizing native species of fish for mosquito larva control and the potential for spawning in captivity of these fish. READ MORE.


image Got Coffee Cans? We Need Them!

Got empty cans and lids? We need them to serve as containers for our mosquitofish program. You recycle. We save tax payers' money. Fish have safe transportation to your home. Please bring in your cans and lids to our office Monday through Friday, 8:00 a.m. to 4:30 p.m. Click here for directions.

Return to Top