Heniochus is a genus of marine ray-finned fish, butterflyfishes from the family Chaetodontidae. They are native to the Indo-Pacific. Though very similar in appearance to the Moorish idol (Zanclus cornutus), the members of this genus are not closely related to it.
Heniochus species are distinguished within the Chaetodontidae by having the fourth spine in the dorsal fin elongated, or even forming a filament. The supraorbital crests in adults have spines or horn-like protuberances. They normally have a hump, or at least a robust bony growth on the nape.[2]
Heniochus is Greek for a “carriage driver” or “coachman” and is a reference to the long, filamentous 4th dorsal spine of these fish, resembling the whip of a coachman.[3]