Gambusia is a large genus of viviparous fish in the family Poeciliidae (order Cyprinodontiformes).

The genus Gambusia comes from the Cuban term, "Gambusino", which means "free-lance miner".

[4][5] As a consequence, they have been introduced widely outside their native range, and frequently become invasive, threatening local species.

[6] G. affinis and G. holbrooki are now established in many parts of the world and are likely to continue to spread as climatic conditions change.

[7] They are only occasionally kept in aquariums, due to their relative lack of color and the highly aggressive nature of the aforementioned mosquitofish species.