My Emperator eats coral. He takes a quarter inch off at a time and chews it up while i watch. Its a large tank and the corals grow fast. Many of the corals are over 12 inches accross and the big one is well over three feet on some axes. Dont fool yourselves, adult Emperators eat sps, they dont "nip". A lot of my other fish "mouth" the corals for slime but the Emperator bites off the end. I wouldnt be able to keep him in a smaller tank. One of the reasons I went to a larger system from my old 180 was to give this guy enough room to grow up into. He was a juvenle when i got him and did the full color change in this system. No way I could keep him in with these sps without this much room. I hope everyone realizes this post is supposed to make you laugh.......not go get an angel fish.