King angelfish
(Holacanthus passer)

Holacanthus passer (king angelfish or passer angelfish) is a large marine angelfish of the family Pomacanthidae. Its large size and bright colors make it a popular aquarium fish, even though it can be difficult to keep.

Distribution
The king angelfish is a non-migratory tropical fish that inhabits reefs in the eastern Pacific Ocean from the coast of Peru north to the Gulf of California, including offshore islands as far west as the Galapagos, generally at depth of 4–30 metres (13–98 ft).

Description
Males and females are visually identical. They do, however undergo significant changes in coloration and to a lesser degree shape as they mature. Juvenile king angelfish are primarily yellow, with fins rimmed with iridescent blue, blue striping towards the posterior of their bodies, and an orange mask around the eye.

Sexually mature king angelfish, on the other hand, have mostly brown or blue bodies (depending on the light) with the same blue rimming around the fins and a yellow tail.

King angelfish generally grow to 35 cm long.

They have between 18 and 20 rays in their dorsal fin and each of their pectoral fins, and 17 to 19 in their anal fin.

They also have a strong spike under their lower cheek for defensive purposes.

Habitat and diet
King angelfish primarily inhabit the middle and bottom of the water column of rocky tropical reefs, including in the larger crevices between rocks, and juveniles can occasionally be found in tide pools. They are diurnal and feed on sponges, other sessile invertebrates, zooplankton, and certain species of benthic microalgae. King angelfish also clean scalloped hammerhead sharks.