There are two species of Platy, Xiphophorus maculatus, and Xiphophorus variatus. Platys are closely related to Swordtails and Xiphophorus helleri, and Xiphophorus maculatus will freely interbreed with Swordtails. The interfertility of Xiphophorus variatus with the others two species may be less, but hybrids can occur. The Platies and Swordtails we buy are often not of pure species.
All three species come from Central America. Xiphophorus variatus, commonly called the Variatus Platy, appears to be able withstand slightly colder conditions than the other two species, and may be more suitable for an unheated tank in a reasonably warm house than the other species, but all are basically tropical fish. Platies tend to be shorter but thicker than Swordtails.
The platy is a tropical fish and I recommend a temperature of 24 degrees C (75 degrees F). They prefer harder water with some salt in it although they are quite adaptable. The platy appears to be better able to survive higher Nitrite (NO2) levels than most fish, but these should normally be avoided for all fish.
The Platy is an omnivore and will eat some algae as well as live food including Mosquito larvae (wrigglers) and Daphnia. They do well on all normal fish foods.
The Platy is a peaceful fish and is a good fish for a community tank of small peaceful fish. The Platy lacks the long fins of the Guppy and is a faster swimmer, so its companions can include some of the slightly aggressive fish that you would not put with Guppies. You need to avoid any large, aggressive or predatory fish.
Suitable companions include Rummy Nose Tetras, Harlequin Rasboras, Guppies, Endlers Guppies, Neon Tetras, Peppered Catfish, White Cloud Mountain Minnows and Zebra Danios. Most of these fish will eat baby Platies.
Never release your pet fish or put them in the position of being accidentally released. The Platy has the potential to seriously damage fragile ecosystems.