I have 2 mollies and a plattie. My white molly has gotten quite fat. Can they gain weight if over fed or do you think it's pregnant? I didn't ask at the pet store if I was buying males or females and the 2 mollies were out of different tanks. The black and white one has stayed the same size and so has the plattie but my white mollie is really big around the tummy and front of the body.