Ctenochaetus binotatus was first formally described in 1955 by the American ichthyologist John Ernest Randall with its type locality given as Batangas Bay, off the island of Luzon, in the Philippines.

The eyes are blue, and there is an obvious dark spot at the rear axils of both the dorsal and anal fins.

In the Pacific Ocean, it can be found as far east as the Tuamotu Islands and Mangareva, and everywhere between southern Japan and New South Wales.

[1] It is found at depths of 60 m (200 ft) in areas of coral and rubble, deep lagoons and seaward reefs.

These fishes feed by scooping up the film of detritus and single-celled algae, such as the dinoflagellate Gambierdiscus toxicus, which is a producer of the ciguatera toxin.