I have a very old flame, coral beauty and a black tail dwarf angel fish. The coral beauty is a model citizen, the flame is so so, the black tail is a nipper. My tank is so full of coral, rarely does one piece get hit often enough to do damage. They don't remove any tissue, they just taste everything, which causes the coral or clam to retract. If it only happens rarely, it isn't an issue, but if they keep at it, the organism gets stressed. I decided I liked the angel fish and gave up on clams, which was bothered the worst. They don't seem to bother my shrooms
at all, nor do my soft or SPS
coral seem to be bothered. They like to hit my frogspawn, but it is as big as a soccer ball, so evidently their attention has done it little harm.