Description
Platies grow to around 2-3 inches (5-7 cm) in size, but dwarf platies (which have been selectively bred for their shorter body length) usually stay around 1 inch (2.5 cm).
As for water quality, Platies are pretty hardy, but generally they prefer temps from 64-77 degrees fahrenheit, a PH of 7.0-8.2, and a hardness (KH) of 10-25, so your tap water, dechlorinated of course, should work. You should feed them a high-quality fish food, and supplement with things like flake foods.