To 3Reef!!! Salutations! Glad to see you found way here!
Fish to be Avoided - Part II (Tropical Fish Forum)
Extremely Aggressive Species:
Undulated Triggerfish (the meanest auqarium fish available in all likelyhood)
Queen Triggerfish (not quite as bad as the Undulated, but pretty close and they get very large)
Clown Triggerfish (pretty similar in demeanor to the above two)
Blueline Triggerfish (not so bad when young but a beast once it grows, perhaps the least aggressive of the four)
Passer Angelfish (probably the meanest of all Angelfish, I've seen them take over tanks)
Damselfish (they're not all bad, but ounce for ounce some of them are the meanest fish around, think twice about adding them as some of your first specimens)
Maroon Clownfish (females get quite large and they can get quite mean and bully any tankmates that dare come close, they're also probably the least tolerant of other clown species)
Sohal Tang (hardier than the Clown Tang but just about as mean, probably best to keep them as the lone Tang and if you must keep one in a community reef tank make it your last fish addition)