The platy (Xiphophorus maculatus) is a species of freshwater fish in family Poeciliidae of order Cyprinodontiformes. It is a live-bearer, that is native to an area of North and Central America stretching from Veracruz, Mexico, to northern Belize. The platy grows to a maximum overall length of 2.4 inches. Sexual dimorphism is slight, the male’s caudal fin being more pointed. The anal fin of the male fish has evolved into a gonopodium, a stick-shaped organ used for reproduction. The female southern platyfish’s anal fin is fan shaped. X. maculatus prefers slow-moving waters of canals, ditches, and warm springs. Omnivorous, its diet includes both plants and small crustaceans, insects, and annelid worms.
Breeders have developed a multitude of color varieties (e.g. orange, red, yellow, red/black, and black/white) which are common aquarium fish for hobbyists. Platies are easy to keep and well suited to a community aquarium. They prefer water with a 7.0–8.0 pH, a water hardness of 9.0–19.0 dGH, and a temperature range of 64–77 °F.
In captivity, they reach maturity in three to four months, and breed readily, the females giving birth to about 20–40 young at a time. Often young are eaten by the adults or other inhabitants of a communal aquarium but given plants and gravel to hide in, some will probably survive as these are hardy fish. Platy young are first seen at approx 7mm long and will use cover to hide from predators and to look for food. Specialist fry food is available but any flake food, frozen or live food that floats their way will be easily consumed. These require excellent water quality.