it won't affect him physically, just aesthetically. fish can really do some miracle healing sometimes though. i had one male Honduran red point that had been attacked by another male - his tail was gone, just a stump of flesh left, no fin at all, and the rear of the dorsal fin was damaged as well, down to the back of the fish. it took 2-3 months, but now you'd never ever know he'd been injured - full tail, no scarring, long perfect streamer coming from the once-missing dorsal. keep the water very very clean, and feed high-quality protein.