Well,
Here is my guess. It doesn't closely match any grouper that I'm familiar with, but it is most likely in the genus Cephalopholis. It looks to me like it is a long-term captive. Groupers held in captivity sometimes develop color patterns unlike that seen in the wild. My guess is that it is either a C. miniatus that has picked up some of its juvenile coloration (the yellow on the caudal peduncle) or it is a C. microprion that has more intense coloration than normal. I've never heard of groupers hybridizing, but I suppose they could (although many groupers are group spawners, and are unlikely to mistakenly pair up with a different species like a lone butterflyfish will).
Jay Hemdal