Ctenochaetus flavicauda, the whitetail bristletooth or redspotted tang, is a species of marine ray-finned fish belonging to the family Acanthuridae which includes the surgeonfishes, unicornfishes and tangs.

Ctenochaetus flavicauda was first formally described in 1938 by the American zoologist Henry Weed Fowler with its type locality given as Takaroa in the Tuamotu Islands of French Polynesia.

[2] The type specimen was collected on the George Vanderbilt South Pacific Expedition of 1937.

[4] Ctenochaetus flavicauda has the specific name flavicauda, meaning "yellow tail", which is a reference to what Fowler described as its "brilliant yellow caudal fin", although subsequent authors have described the caudal fin as pure white.

[3] The brilliant white caudal fin contrasts sharply with the rest of the body.