ledges and within caves. The subadults are frequently recorded in cavities in reefs and along surge channels on seaward reefs. The juveniles frequently shelter below ledges, in reef cavities and in relatively sheltered areas in channels and over outer reef flats. It’s diet comprises sponges and other encrusting organisms, as well as tunicates. They form pairs. The juveniles and adults may act as cleaner fish, cleaning ectoparasites off larger fishes. When frightened, these fish can produce a knocking sound. Systematics The emperor angelfish was first formally described in 1787 as Chaetodon imperator by the German physician and naturalist Marcus Elieser Bloch (1723–1799) with the type locality given as Japan. Some authorities place this species in the subgenus Acanthochaetodon. The specific name imperator means “emperor” and reflects the Dutch name Keyser van Iapan meaning “Emperor of Japan” coined by the publisher Louis Renard (ca. 1678-1746) in 1719, possibly reflecting its majestic appearance. Utilisation The emperor angelfish is common in the aquarium trade. References External links Froese, R. and D. Pauly, Eds. Pomacanthus imperator. FishBase. 2017. Schofield, P. J. Pomacanthus imperator. U.S. Geological Survey, Nonindigenous Aquatic Species Database. Emperor Angelfish. National Aquarium. Pomacanthus Fish of Palau Fish described in 1787