I did have a coral beauty and a bi-color. The coral beauty was so laid back all it did was eat algae of the rocks. The bi-color pretty much kept to himself. Due to a tank crash a couple of years ago, I lost them both. Now I have a flame angel and he is very aggresive and would definitely not tolerate another dwarf in the tank. The point being, angels differ and as a general rule the bigger the tank the better. And adding them at the same time would be a good move.