The best visual way to sex oscars is venting and cannot be done until they reach 6'' or more and even then it's very difficult even to the trained eye.
OO-female
Oo-male
My Big Red Oscar has become so calm now.....It totally disregards every other fish.
I threw in a 3.5" Albino Tiger the other day and now they are swimming together. (Probly showing the new little guy around ) Damn I love these things....their always so curious and moving about in a calm fashion.....
I love petting them too
I know in the future I'm gonna have to make a choice between Oscars or Jaguar when that Jag hits maturity....but for now, they are all friends, swimming together!