Care: 
Expert
Diet: 
Omnivorous
Light: 
Medium
Place of origin: 
Western Indian Ocean
AKA: 
Chaetodon diacanthus - Holacanthus diacanthus
Indo-West Pacific, ranging from Red Sea and east coast of Africa, through most Indian Ocean islands to Western Pacific from Japan to Australia and Pacific east to the Tuamotu Archipelago. Occurs in coral-rich lagoons on shallow reef flats and along walls near caves or ledges to depths of 80m  where they feed primarily  on certain sponges. Juveniles secretive in caves and usually seen solitary. Adults in pairs and occasionally in small groups. Readily identified by the patterns of many alternating orange, blue and white vertical stripes. Two distinct colour variations between Pacific and Indian Ocean. Most obvious in adults is the grey  (Pacific) versus yellow  (Indian) chest. Being more colourful in general makes the Indian Ocean form more popular amongst aquarists. Juvenlies are similar to adults but feature a distinct ocellus at the rear of the base of the dorsal fin. Aberrations in the striped pattern are quite common and occasionally yellow looking individuals, lacking dark pigments, are sighted in both the Indian and Pacific Oceans. Length to 25cm. 
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.