The family is native to lower elevations of eastern United States, Argentina and Africa. The only species that is established in NY is native to areas south of Kentucky, Illinois and Missouri. It is also known to occur in salt waters in coastal areas. Some species have all-female individuals, and the eggs can develop when stimulated by the sperm without fertilization.
Western Mosquitofish live in quiet backwaters and ditches. It is native to the southern US and is apparently intolerant of temperate winter conditions. It has been established in two watersheds near NYC since only 1979.