Ctenochaetus flavicauda is a Tang from the Pacific Ocean. It occasionally makes its way into the aquarium trade. It grows to a size of 11.8 cm (4.6 in) in length, making it the smallest ctenochaetus tang, and also the smallest acanthurid. As a juvenile it is a bright yellow color, as an adult it is reddish brown color with orange colored fine horizontal striping, the tail is white and the eye is ringed by bright yellow. The species was first described in 1938 by Henry W. Fowler from a specimen collected near Takaroa in 1937 by the George Vanderbilt South Pacific Expedition.