Most dwarf angels (with maybe the exception of the atlantic pygmy or african flameback) may have a tendency to peck at certain reef inhabitants, mostly clams and scallops. If you don't plan on having mullusks in the tank I wouldn't worry too much on what kind to get. I have a coral beauty that only grazes on the rocks and doesn't touch any coral. As stated, all fish are hit or miss. Personally, I love dwarf angels and probably will never have a tank without one!