The green swordtail (Xiphophorus hellerii) is a species of freshwater/brackish fish in family Poeciliidae of order Cyprinodontiformes. A live-bearer, it is closely related to the southern platyfish or "platy" (X. maculatus) and can crossbreed with it. It is native to an area of North and Central America stretching from Veracruz, Mexico, to northwestern Honduras.