The Beau Gregory Damselfish is an overly aggressive fish, so usually only one should be kept per tank. An aquarium of 50 gallons or larger will provide a suitable environment. They are the king of the tank, big or small, they will dominate your tank. Although very aggressive they are considered reef safe. The Beau Gregory Damselfish is a very popular fish at all our dive sites! They feed on a variety of meaty items, herbivore preparations, and flaked foods.