Looks like a warmouth to me, I have heard of this happening before with other natives.
You have oscars right? Their care is very similer to oscars and other cichlids. If he won't take dry foods try stuff like worms and frozen foods, eventually he should start eating dry foods though. The only sunfish I have had a problem converting were crappie and largemouth/smallmouth bass.
Nice find! I'd be careful what you pu in with it, b/c any of the breams can be annoying little b*stards once they've staked out a territory. Every once in a while, we'll get crazy crap like that mixed in with feeder goldies at work. Recently we've been getting a lot of american eels...go figure. Good luck!