Genicanthus personatus

Lore & Background

Genicanthus personatus is largely a brilliant white color at all ages. Juveniles have an area of black covering most of the head; as the fish grows, the black breaks up, starting with the lips turning bluish white and the caudal fins darkening to black. Like all marine angelfish, it is a sequential protogynous hermaphrodite: younger sexually mature adults are all females. The black on the head reduces in extent, eventually only surrounding the eyes, on the chin, and along the edge of the operculum and its spine. They also have yellow pelvic fins. Once they reach a length of 15 to 18 cm, they may change sex to males. When they do, they develop vivid orange-yellow pigmentation on the pectoral fins, the whole face, and the margins of the dorsal, anal, and pelvic fins. Males develop long filamentous extensions to the caudal fin lobes. The species attains a maximum total length of 21 cm.

Reader's Guide

Genicanthus personatus is endemic to the Hawaiian Islands, with higher numbers in the northwestern islands. It is found at depths between 10 and 150 m over rocky reefs and on outer slopes of reefs. Its diet comprises green algae in the genus Codium, planktonic organisms, and fish eggs. The species was first formally described in 1975 by American ichthyologist John Ernest Randall, with the type locality given as Honolulu on Oahu. The specific name personatus means 'masked.' In the aquarium trade, it is very rare and commands high prices; it has been bred in captivity. Its protogynous hermaphroditism and dramatic color changes with sex transition make it a notable subject for study and collection.

Did You Know?

• Genicanthus personatus is endemic to Hawaii, more numerous in the northwestern islands.
• Juveniles have a black head covering that breaks up as they grow, leaving only black around the eyes, chin, and operculum edge.
• Males develop vivid orange-yellow pigmentation on the face and fins, plus long filamentous caudal fin lobes.
• It was first formally described in 1975 by John Ernest Randall, with type locality Honolulu on Oahu.