Tropical Fish Centre - Livebearers Livebearers Mostly native to Central America, these small, colourful fish are very popular because they are very hardy and inhabit all levels of the aquarium. Platys are probably the best example, a very good choice for a aquarium which has just started. With enough space the dorsal fin can become very big. This is normally a very active fish. Can get very big.
Females tend to be larger and more duller.
It isn't unknown for a female to change into a male, especially when affected by parasites. The platy is a peaceful, hardy fish and was my first fish.