Eastern mosquitofish

The eastern mosquitofish (Gambusia holbrooki) is a species of freshwater fish, closely related to the western mosquitofish, Gambusia affinis. It is a member of the family Poeciliidae of order Cyprinodontiformes. The eastern mosquitofish is native to the eastern and southern United States from Florida to Delaware and inland to Alabama and Tennessee, while the western mosquitofish has a larger distribution throughout the United States.

Description

The Eastern mosquitofish is a small, light-colored fish with semitransparent fins. The females usually have a black stripe near their eye area and light spots can be seen on the caudal and dorsal fins of both sexes. Due to its similar size, shape, and reproductive habits, it can easily be mistaken for a guppy. Generally, males reach 1.5 in (3.8 cm) and females 2.5 in (6.4 cm). These fish are a livebearer species, and as such, the females are larger and more rounded than the males. Pregnant females are also easily recognizable by their gravid spot; a darker area on their bellies where they hold the fry.