Hey just had a thought , I know he is nipping at corals and i do hate to kill any fish but maybe you get him close to a hose that is hooked to a pump and suck him up into it. Kinda like a shop vac or even a return pump . I've seen your tank and rock work ....with all your corals I think a capture would be nearly impossible. Maybe with netting over the hose the suction might be strong enough to hold him to it so he doesnt end up like a racing clown did ......and with a return pump you could just put the water back in your over flow. Just a wild thought so good luck Troy.