How can you tell if an oscar fish is a girl or boy?

Answer by  toadie (25)

It can be really difficult to tell until they are sexually mature. They don't show sexual dimorphism (differences in appearance between sexes). When they are ready to spawn the female will have a protuding vent that is wider than the males. Get at least 6 individuals and raise them together to ensure you are getting a pair.

Answer by  chet13 (332)

The easiest way to tell is to observe it's behavior with other oscar fish. If the fish is biting the other oscars, it is most likely a male, also if the fish seems to always chase the other oscars and corner them, it is most likely a male.

Answer by  EddyNfld (147)

Oscar fish are a very hard fish to sex. Some say that females grow larger than males, some say that females are brighter color than males. One physiological way of concluding sex is to look at the anal fin. If it is longer then most likely it is a male.

Answer by  Brit7any (115)

Watch for the eggs to be laid, females lay the eggs and the male has a tiny spike looking organ that will come out at sexual maturity.