Females and immature males are green above with dark edge scales on their back and sides, and yellow below. Mature males are usually red below, with a black stripe along their sides and a yellow-orange to red colored sword. These same authors found immature males to inhabit shallower waters approximately 20 cm in depth. Green swordtails live in mixed, hierarchically structured groups. Dominant males held home-ranges and dominant positions over periods of many days to weeks.
Green swordtails are prolific live-bearers.
Museum records exist for Brevard, Hillsborough, Palm Beach, and Polk counties, Florida. However, the present status of this species in Texas is uncertain. Green swordtails are very popular aquarium fish, and as such, are commercially valuable. Because of their small size, they are of no value as food fish. The green swordtail was formerly established in Florida.