Adult Emperor Angelfish have dramatic diagonal stripes in yellow and indigo. Divers in the Indian and Pacific Oceans can also recognize mature Emperor Angelfish, Pomacanthus imperator, by their white snouts. Young Emperor Angelfish look dramatically different than the adults. Like many angelfish in the family Pomacanthus, Emperor Angelfish start life with one set of colors and patterns and change to an entirely different set as they mature (the emperors new clothes?).

This makes Emperor Angelfish especially fascinating for divers to find. Juveniles have concentric white rings on a dark purplish-blue body. Adults have the stripes shown above. Observant divers can sometimes find these angelfish with a mix of the two patterns as they are changing their patterns.