I have a Platys in with Two other much larger goldfish.?

Question

Its belly had recently GROWN. It looks like its going to give birth. How can that be?

Answer 1

Platies and goldfish are both cool water fish. They prefer temperatures from 70F-75F. They are fine together.
Female platies can store sperm and give birth for up to 6 months after being seperated from any males. Either your platy is indeed pregnant or it has the disease called dropsy, which you should look up on a search engine.
Platies often get aggressive with goldfish because they like to eat the slimecoating off the goldfish scales. If your platy starts to do this you should seperate them.

Answer 2

yes helen h is right, platys are freshwater and goldfish are coldwater fish. Maybe your platy was already pregnant. also platys give birth to tiny live fish >>> goldfish lay eggs. They give birth to different types of young so it Must have already been pregnant.

Answer 3

forgive me i thought platys were tropical fish and goldfish were coldwater fish(who is inwrong temerature water???).your platy could have been pregnant when you bought it or it could have bloat disease.