Dwarf angels are divided into 2 subgenuses. The first Centropyge has lips that are nearly equal in size and includes Bicolors, Eiblis, halfblacks, lemonpeels, keyholes, and heralds amongst a few others and all tend to be poor choices as far as reef safeness is concerned. The second subgenus is Xiphipops which includes Argis, Flamebacks, Coral Beauties, Rusties, potters, multicolors, and repslendants and are most easily identified by their smaller lower lip which makes their jaw look more underslung. They tend to be much more reef safe than the first group but still might pick. There is also a thrid genus/subgenus depending on who you pay attention to that has three members the venustus, multibar, and peoppermint. Not as much info on these guys though what is otu there is that they are more towards the reef safe side.