MOSQUITOFISH (Gambusia affinis)
The most successful biological tool against immature mosquitoes in California is the mosquitofish, Gambusia affinis. When introduced to a mosquito breeding source, the mosquitofish quickly adapts, multiplies and is capable of controlling mosquitoes in a given area.

The mosquitofish, a live-bearing American fish, is utilized as a predator of mosquito larvae in many diverse aquatic habitats. A small species, the full-grown females are usually less than 2½ inches in total length, while males are typically under 1½ inches. The muted silver and light olive green body color is common to both sexes. In addition, they are able to lighten or darken their body color to closely match their immediate environment.

GUPPIES (Poecilia reticulata)
The guppy, Poecilia reticulata, has been used for biological mosquito control since World War I. It has been introduced almost all over the world from the areas of tropical South America to which it is native. In many areas, the guppy has provided good control of mosquitoes in highly polluted sources, such as sewage pools, dairy lagoons, chicken ranch ditches and slightly acidic sources. Unlike the mosquitofish, the guppy’s ability to reproduce or control mosquitoes is not reduced by low levels of dissolved oxygen.