The members of the family Pomacanthidae are generally know as angelfishes and, like their nearest cousins, the butterflyfishes, are regarded by many divers and aquarists as being amongst the most beautiful and majestic fishes in the sea. The majority of species occur on shallow reefs in coral, algae and sponge zones, most going little deeper than about 30m but where conditions are pristine and water is very clear, many species go much deeper and few species only live deep (over 100m). Angelfishes feature a large and distinctive backward-protruding spine from the lower corner of the gill-plate (cheek spine) from which the family name was derived. This cheek-spine is diagnostic for all the species , even at juvenile stage, and readily separates any angelfishes from butterflyfishes that may be similar in shape. Mot angelfishes are robust with compressed, ovate to rhomboid shaped bodies, covered with small or tiny scales, and have a continuous dorsal fin. The mouth is small and jaws are set with many small, usually tricuspid teeth that are used for grazing algae or scraping sponges and other sessile invertebrates. Few species combine their diet with a variety of foods and some are planktivores.
Tropical eastern Pacific, form the Gulf of California south to Peru, the Galápagos and mexican Revilla Gigedos Islands. Occurs in rocky and coral habitats at depths between 5 and 30m. The Cortez angelfish either lives singly, in pairs and may also form aggregations. Adults are dark in appearance and have a large yellow area reaching from the forehead to the breast. There is a broad sickle-shaped body stripe behind the pectoral fins. Juveniles are very similarly patterned to juveniles of Pomacanthus semicirculatus, but the semicircular lines of this species are yellow rather than white as in juvenile P.paru and P.arcuatus from the western Atlantic. Length to 45cm.