Genus of small, livebearing freshwater fishes with current taxonomic classification:
Superorder: Acanthopterygii (spiny-rayed fishes)
Order: Atheriniformes
Family: Poeciliidae
Genus: Gambusia
Gambusia resemble guppies in shape and size but are much less colorful: their bodies are typically olive gray with some black markings and perhaps a slight irridescent blue sheen. They are the northernmost members of the Poeciliidae family, ranging from Panama north through Texas, across the Gulf and Atlantic coasts to New Jersey and up the Mississippi basin to Illinois. They are also found in several Carribean islands.
Gambusia are often called mosquito fish because they are used widely to control mosquito larvae. They are hardy, prolific, and have been introduced to many other parts of the world with disasterous ecological effects. They have, for example, caused significant damage to populations of native fish in Australia and New Zealand. They have also been linked to the decline in numbers of certain kinds of frogs and newts in California and the disappearance of various desert fish in the U.S. southwest.
At last count, 32 species of Gambusia have been described. Many from Texas and Mexico are either endangered or believed to be extinct. The two most well known species are: