I definitely wouldn't put a trigger in a frag tank, that's the proverbial "bull in a china shop". In my 90, I just secure the frags with IC Gel and/or epoxy. The trigger doesn't nibble on the corals or rocks, he's totally a predator. He's just such a beautiful, cool fish to watch, kind of the "Dennis the Menace" of the tank.
BTW, sorry for the hijack, clock'