The Poeciliinae are predominantly freshwater fish but some species live in brackish water, and some can even tolerate seawater. They are found in North America as far north as southern Canada, Central America and South America through to
Patagonia. Some of the world's most popular
aquarium fish such as guppies, swordtails and mollies are from this subfamily. For example, the
Eastern mosquitofish Gambusia holbrooki is considered to be one of the 100 worst invasive species in the world and is responsible for declines in small native aquatic species worldwide. ==Subdivisions==