The Emperor Angelfish is native to reefs of the Indian and Pacific Oceans.
Adults, with their attractive bright yellow and blue body lines and white face with purple-edged bandit mask,
reach some 40 cm long.
They usually form pairs. When frightened, they can make a knocking sound.
Diet is variable but they particularly eat algae, sponges and tunicates.
Adults of Pacific Ocean reefs often have a trailing dorsal fin filament (shown top row), whereas
those of the Indian Ocean have a rounded dorsal fin end (shown in row above and below).
Juveniles (sub-adult above) look very different with a dark blue background and white, circular and semi-circular lines.
Both juveniles and even adults have been known to work as cleaner fish to larger fish species.