All angels are only reef-safe to a certain extent. Most will occasionally nip at coral polyps and clam mantles, and may eat soft corals, but usually do not do irreparable damage. Angels are also very sensitive to water quality, and many do not fare very well in the aquarium setting. Cherub angels are one of the better aquarium fishes, although once established can become rather aggressive toward doscile tankmates. Coral Beauty angels are another decent fish, and are somewhat less aggressive than many other angels.Flame angels are fairly good fish, but to be less aggressive, should be the last fish introduced into the aquarium. The watanabe's angel, although not a pygmy at 6" max length, is an excellent agnel for the reef aquarium, but sadly most in the aquarium trade suffer from swim bladder damage and should be avoided. Healthy specimens readily acclimate to the home aquarium, moreso in a deep-water tank.