The male green swordtail grows to a maximum overall length of 14 cm (5.5 in) and the female to 16 cm (6.3 in). The name "swordtail" is derived from the elongated lower lobe of the male's caudal fin (tailfin). Sexual dimorphism is moderate, with the female being larger than the male, but lacking the "sword". The wild form is olive green in color, with a red or brown lateral stripe and speckles on the dorsal and, sometimes, caudal fins. The male's "sword" is yellow, edged in black below. Captive breeding has produced many color varieties, including black, red, and many patterns thereof, for the aquarium hobby.