Threadfin Butterflyfish

The Threadfin Butterflyfish (Chaetodon auriga) is a marine ray-finned fish within the family Chaetodontidae, notable for its extensive distribution in the Indo-Pacific region.

This species inhabits the Indo-Pacific area, ranging from the 🌊 Red Sea and eastern Africa (extending to Mossel Bay, 🇿🇦 South Africa) through the Hawaiian, Marquesas, and Ducie islands, reaching northern latitudes as far as southern 🇯🇵 Japan and southern limits to Lord Howe Island and Rapa Iti. It is typically found at depths ranging from 1 to 35 meters (3 to 115 feet). In 2015, a single specimen was observed in the western Mediterranean Sea near Italy, likely due to aquarium release.

Chaetodon auriga can attain a length of up to 23 centimeters (9 inches). The species is characterized by a white body adorned with distinctive "chevron" markings along the sides. A notable black spot is present at the rear edge of the dorsal fin, accompanied by a trailing filament, while a black vertical band crosses through the eye. The fish's belly features a pattern of descending oblique dark lines, and its fins display a vivid yellow coloration. Two subspecies are occasionally identified: Chaetodon auriga auriga, found in the 🌊 Red Sea and lacking the dorsal eyespot, and Chaetodon auriga setifer, which includes the spotted population outside the 🌊 Red Sea.

Chaetodon auriga is classified within the subgenus Rabdophorus, which may be considered for recognition as a distinct genus. Within this subgenus, it is closely related to the Vagabond Butterflyfish (C. vagabundus) and the 🇮🇳 Indian Vagabond Butterflyfish (C. decussatus). The C. auriga species group is distinguished by a pattern of two areas of oblique lines that ascend and descend, differing mainly in coloration of their hindparts.