Yellow Tang coral nibbler?
Over the last week I have noticed my Tang nipping at my red open brain.
65 gal reef
2 PC's 192W each , 20 gal sump/fuge
4 false clowns, 2 firefish, cardinal, midas blennie, toadstool, zoos, shrooms, trumpet coral, torch, pagoda, frogspawn, poylps, red open brain, devils hand, hermits, snails, 3 cleaner shrimp, coral banded and a emerald crab.