King Angelfish

Adult king angelfish are generally about 35 cm in length. 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. H. passer also possess a strong spike under their lower cheek for defense. King angelfish undergo significant changes in coloration as they mature. Juvenile king angelfish are primarily orange-yellow including the pectoral and pelvic fins, rounded dorsal and anal 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), light yellow pectoral and pelvic fins, a yellow patch on the mouth, the same blue rimming around the dorsal and anal fins, and a yellow caudal tail.

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).

King angelfish are diurnal and feed on sponges, other sessile invertebrates, zooplankton, and certain species of benthic microalgae. H. passer spend the majority of time foraging in the middle of the water column feeding on zooplankton or in benthic communities grazing on algae. Foraging site selection differs with demography because females and small fish graze more frequently in benthic communities whereas males and large fish feed more frequently in the water column. In the Mexican Pacific Ocean, king angelfish are vital spongivores and were observed to consume up to 23 out of 24 different species of sponge surveyed with a specific preference for the order Hadromerida.

King angelfish are monogamous within their pairs, and during their spawning cycle, will mate daily around sunset. The fish are broadcast spawners and currently their larval duration is currently unknown. During a spawning cycle a pair can produce upwards of ten million fertilized eggs, averaging about 25,000–75,000 daily. These eggs then drift in the water column for about 20 hours, at which point they hatch. After hatching, the finless fry live off their yolk sack until it is completely absorbed, at which point they begin to eat small zooplankton.

The king angelfish conservation status is deemed least concern by the IUCN red list. However, the Conservation Regulation of Mexico granted the status of special protection to the king angelfish in 1996 due to overfishing, thus the harvest of this fish was limited and caused two fisheries in the Gulf of California to close in the early 2000s. After the fishing ban, the species seemed to recover, but unfortunately, there is no population density data on its presence in Latin America.