Mosquito Fish, Friend or Foe?

by Bill Templin


Mosquito fish (Gambusia sp.) are small fish
(1.5 – 2.5 inches) that tolerate a wide range of temperatures
and are used as a predator of mosquito larvae in many diverse aquatic
habitats throughout the world. With all of the attention being given
locally to aerial spraying to control mosquitoes and reduce West Nile
Virus problems, mosquito fish just keep on quietly eating the mosquito
larvae as many people want them to do. Unfortunately, mosquito fish
also eat other living things, which can be a problem in some environments.
In fact, some people think that mosquito fish can be a “major pest and
in many cases more suitable alternatives exist for mosquito larvae control”

So what should we use for mosquito control if we
can’t use mosquito fish? Pretty much any fish will eat mosquito
larvae. Try finding a mosquito larva in any body of water inhabited by
fish. The best thing to use is a native fish found in your local area
that is somewhat hardy and will reproduce in the environment that requires
mosquito control. Guppies (Poecilia sp.) are also used locally instead
of mosquito fish, mainly in koi and gold fish ponds, but they lack the
tolerance for temperature extremes. For more information, visit the

Sacramento-Yolo Mosquito Vector Control District

During a recent tour of the Sacramento-Yolo Mosquito & Vector Control
District offices and hatchery facilities, I learned that mosquito fish
and guppies are used as biological controls to help reduce the amount
of pesticides needed. Mosquito fish are planted in most permanent or
semi-permanent water sources but are no longer planted in vernal pools
because of their detrimental impacts on fairy shrimp. I also learned
that planting is now done only by technicians who are trained in the
field. In the past, mosquito fish were handed out on request, which
provided less control on their use. I also found that District Manager
David Brown (dabrown at FIGHTtheBITE dot net) and his staff are very helpful
and eager to work with individuals and groups who may have concerns
about any of the District’s operations. Consider taking a tour yourself.
They will be holding an Open House next spring.

This article originally appeared in our Summer 2007 Newsletter


Leave a Reply

Your email address will not be published. Required fields are marked *