How to tell male and female Oscar fish (map fish) apart?

Map fish can generally be sexed by their outward appearance, because male map fish have a raised bump on the head, while females do not. In addition, male map fish have relatively pointed upper and lower fins, whereas the female’s fins are rounder.

Beyond that, you can distinguish them by the genital pore. Female map fish generally have a larger abdomen, with a genital pore noticeably larger than the anus, while males are flatter, with a genital pore about the same size as the anus.