Wisconsin Department of Natural Resources

Western Mosquitofish

Source: Wisconsin DNR Aquatic Invasive Species program

Date: Data continuously updated. Metadata last updated 2/2012

This data represents waterbodies where the Western Mosquitofish are known to exist. This nonnative and invasive fish species may be growing in other waterbodies, but its presence has not been confirmed outside of the waters listed here. Western Mosquitofish monitoring is conducted on Wisconsin’s lakes and streams in the summer months, with the infestation data compiled in the fall. The data here is current through the 2011 monitoring season.

Western Mosquitofish are small, dull grey, with a large abdomen. They have rounded dorsal and caudal fins and an upturned mouth towards the surface. Mature males may grow to be about 1.6 inches and females 2.8 inches in length and generally resemble a guppy. The name Mosquitofish was given because their diet consists of large amounts of mosquito larvae.

For more information, please visit the Invasive Species pages.