I already have a six-line wrasse, so I guess it's not nudi's in my case. What other fish are good at protecting zoo's? I have a copperband butterfly, a yellow tang, a blue damsel, and maroon clown. The marron clown sometimes knocks down rocks, but I haven't seen him biting any zoo's. The butterfly likes to pick around all of the corals, but have never seen it actually biting a coral (and I've spent lots of hours watching it). Should I just take the zoos out and look at the rock more closely?