Yes, this is a female.is this a female molly?
oh my god it then links the store....Do you have other fish in the tank? I would immediately move her from the tank. this can probably spread to other fish. i can tell you what you need for a hospice tank if you need help. it looks like a tumor, but I know it's a living part BC it has blood vessels in it (zoom in on the middle part) I would consult a vet or exotic pet vet. DON'T ask petsmart, they know N.O.T.H.I.N.G. BTW, she is SOOOOOOO cute!