Mosquitofish are available for pickup at the District's office at 155 Mason Circle in Concord Monday through Friday (except holidays) from 8:00 a.m. to 4:30 p.m. Containers are provided. One fish per every four square feet of a water feature's total surface area is how we determine how many fish to provide to residents. Please call in advance (925) 685-9301 if you need large numbers (50 or more) for a water feature such as a swimming pool or large pond. This applies to residents who are going to obtain fish from the District office ONLY).
This hearty species of guppy can survive various water quality conditions and temperatures as well as reproduce often. Learn more about caring for mosquitofish by clicking here.
Mosquitofish may be used in ornamental ponds, horse troughs, stock ponds and other artificial water bodies and may not be placed by the public in creeks or natural water sources.
How Do Fish Control Mosquitoes?
As a natural predator of mosquito larvae, mosquitofish have been used for mosquito control purposes throughout the world for many years. They have a voracious appetite. Each fish can eat up to 500 mosquito larvae per fish per day! More than 1 million of these fish are produced each year at the Contra Costa Mosquito Vector Control District's mosquitofish production facility, which requires specialized care in a specific, controlled environment. These fish are routinely stocked by technicians to control mosquito populations throughout the county. They are often placed in neglected swimming pools (pools that are not chlorinated or filtered). Pools in this condition can potentially produce up to 1 million mosquitoes per swimming pool, even partially filled pools. Residents can also place these fish in their own neglected swimming pools (ideally, the Contra Costa Mosquito & Vector Control District would appreciate residents properly maintaining their swimming pools by ensuring they are chlorinated and filtered).
By law, only vector control technicians can place fish in water sources other than those located on private property. Some common 'sources' or sites where these fish are stocked include; artificial lakes, irrigation ditches, storm channels, and natural industrial ponds. Of course, we encourage residents to get free fish from our District to take home and place in their own backyard pond, horse trough, or neglected swimming pool.
To avoid competition with sensitive native amphibian and fish species, we do not stock mosquitofish in habitats where such species are known to be present.
Got coffee cans? We need them!
Got empty cans and lids? We need them for our mosquitofish program. You recycle, we save tax payers' money and 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.
We are located at 155 Mason Circle in Concord. Click here for directions.