Go Fish
By John Albright, Biologist - Public Information Specialist, Shasta Mosquito and Vector Control District
Starting a new job can be a real adventure. Anyone who has ever changed careers has most certainly run into their share of surprises when they first embarked on that new journey. The only thing that I was certain of when I began working at Shasta Mosquito and Vector Control District in March of 1997 was that I didn't know what I was in for. So when the guys asked me early on in my new job if I wanted to go fishing on company time I figured it must be some sort of a trick question. In fact they were referring to restocking our mosquito fish tanks. The mosquito fish program is one of our most popular and widely used services. Mosquito Fish, Gambusia affinis, have proved to be an environmentally friendly, and extremely effective way of controlling mosquitoes locally, and literally throughout the world.
Mosquito fish were first introduced to California in 1922 for mosquito control. Since that time they have spread naturally and artificially to permanent water sources throughout California in all but the most hostile, high elevation climates. They originally came from more eastern portions of North America where they ranged from Southern Illinois to Texas, and along the Gulf of Mexico to Rio Panuco Basin, Mexico. They are such an effective and adaptable mosquito predator that they have been exported and used throughout the world for mosquito control. This has caused them to become the most widely distributed freshwater fish on earth.
The use of mosquitofish for mosquito control is one of a number of techniques used in
modern pest
control referred to as biological control. This generally 
involves the artificial introduction of a natural predator, parasite or disease into an area to control
a specific pest. Use of biological control as a method of controlling major pests that
occur on a global scale is an idea that has gained popularity this century. It has partly
become a matter of necessity as the increase in travel and trade around the world has led
to the artificial introduction of exotic pests into new environments. These new, foreign
pests often arrive without the natural enemies needed to keep them in check. Some examples
of biological control that you may be familiar with are the use of ladybugs and praying
mantids in gardens, using cats to control mice around the home, and efforts by agriculture
departments to control such weed pests as yellow star thistle with imported insects.
Mosquitofish have a number of advantages over such things as goldfish and koi for biological mosquito control in ponds and other water sources. For one thing, they actually eat mosquito larvae. They are voracious surface feeders with upturned mouths specially designed to get mosquito larvae where they live. They prefer the cover and protection of shallow overgrown areas along the shore which are also the preferred environs of mosquito larvae. Since they give birth to live young (they are in the guppy family) they don't need any special sand or other substance for spawning. They are self-sustaining and self feeding. If all this doesn't sell you on the idea of using mosquito fish in your pond there is still one other fact that may convince you to give them a try -- they're free!
Shasta Mosquito and Vector Control District maintains an active program of distributing mosquitofish free of charge to anyone within the district with permanent water sources which may harbor the mosquito larvae. Mosquitofish are available at the district office and can be delivered by our field technicians. To obtain mosquitofish or information about mosquito and vector control call the Shasta Mosquito and Vector Control District Office at (530)365-3768.
The information in this web page is also available in a brochure.
For More Information:
(530) 365-3768