The threadfin butterflyfish (Chaetodon auriga) is a species of marine ray-finned fish belonging to the family Chaetodontidae.

[2] A single specimen was reported recently (2015) in the western Mediterranean Sea off Italy, a likely result of aquarium release.

The fish also has a belly patch of descending oblique dark lines and bright yellow fins.

[2] It belongs to the large subgenus Rabdophorus which might warrant recognition as a distinct genus.

The C. auriga species group shares the characteristic pattern of two areas of ascending and descending oblique lines, but they differ conspicuously in hindpart coloration.