Chaetodon austriacus, also known as the Blacktail butterflyfish inhabit areas of dense coral growth throughout the Western Indian Ocean and the Red Sea. The maximum adult size is around 13cm (5.1 in.).
Chaetodon austriacus is very often confused with C. melapterus and C. trifasciatus. However, the anal and caudal fins are black with yellow margins in adults. Juveniles are less colourful than their adult counterparts. They have a large yellow-edged ocellus on the caudal peduncle. The dorsal fin is white with a submarginal border of black in the soft dorsal portion. There is a black bar through the eye and a second bluish-grey bar from the dorsal base to the lower angle of the operculum. The body colouration is predominantly yellow with narrow, bluish stripes that are intense dorsally, becoming indistinct ventrally. A broad horizontal daub of black is present in the third stripe towards the posterior dorsal region.
Chaetodon austriacus feeds in the wild almost exclusively on coral polyps; therefore it is difficult to keep in an aquarium. Some reefer have been coaxed the Blacktail butterflyfish onto alternative foods and these do well but this is the exception, rather than the rule.
Butterflyfish are not recommended for reefs as they will pick at or eat a wide variety of corals, fan worms, and other invertebrates. Most Butterflyfish are known to pick at Aiptaisia, a parasitic anemone.
Chaetodon klunzingeri Kossman & Räuber, 1876
Chaetodon trifasciatus austriacus Rüppell, 1836
Chaetodon trifasciatus klunzingeri Kossman & Räuber, 1877
Citharoedus austriacus (Rüppell, 1836)