Besides groupers, well: Lionfish, Large Wrasse, large eels, big angelfish probably won't get eaten, but the water quality could cause a problem. So almost any large, hardy fish that can is somewhat aggressive (execpt for triggers and files) and fish that have aggressive spines could survive (lions, foxfaces). Or you could get another small shark like a bamboo. Keep us updated, and risc will know more on this subject than I would.
-Mark