Wow thanks for all that information! I didn’t know that it had a mutation. I will definitely not be breeding this fish as I would hate to pass it on to the babies! The only reason I would be breeding fish is I have a 300L tank that I would only like to have fish I have bred in it. Thanks again for the info really helpful!To me, that appears to be a fish with a problem - a balloon mutation. The deformity makes them harder to sex, and while opinions differ, I wouldn't worry about their sex. They shouldn't be bred, as the deformity is serious and possibly painful.
They're popular fish, and my view can be dismissed. I think, from its size, that it's a female.