I realize this thread is a little old but I just had to answer. A relative of mine was fishing in Lake Woodlands (a man-made lake in Texas) and he caught a fish that was the size of a full grown oscar with the same coloration of an adult tiger oscar but it had a forked tail and I swear it looked like a perch/oscar hybrid. He put him in his tank with his adult oscar and after a bit of fighting they cohabitated for several years before they died after a power outage. I now wish I would have taken a picture of him.
i know this thread is probably way past from having any posts. but i thought i might want to shed some light on maybe the cause of why there arent any oscar crosses. my thoughts on it is maybe there arent any other cichlids that are related close enough to the oscar to breed. and maybe because the oscar doesnt want to breed with any others like a convict would be likely to try!