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.
Indo-west Pacific. Western Pacific from southern Japan to Australia, ranging west into Indian Ocean to the Maldives and Thailand, and east to Vanuatu, Coral Sea. Adults live in coral rich lagoons and along outer reefs in a depth range of about 5 to 35m. The Blue-faced angelfish is shy in most places and usually seen solitary, but occasionally it forms pair which occupy large territories. This species feeds on sponges and tunicates, and makes loud bongo-like sounds when disturbed. Adults are readily identified by their brilliant blue head with an orange mask over the eyes, and have an obvious dark blue round spot on the end of the dorsal fin. Juveniles are bluish black with vertical blue and white lines, the lines being mainly straight on the body. Change from juvenile to adult pattern begins at a length of about 7 cm, and is usually completed when reaching 10 to 12cm. Length to 40cm, common to about 30cm.