Ctenochaetus truncatus was first formally described in 2001 by the American ichthyologist John Ernest Randall and the New Zealand biologist Kendall Clements with its type locality given as La Digue in the Seychelles.

[4] Ctenochaetus truncatus has its dorsal fin supported by 8 spines and between 25 and 27 soft rays while its anal fin is supported by 3 spines and 23 to 25 soft rays.

[5] The lips have a margin which is smooth or has small wart-like bumps.

The caudal, dorsal, anal and pelvic fins have a yellow hue.

[1] This species is found at depths between 1 and 21 m (3 ft 3 in and 68 ft 11 in) over sheltered crests and slopes of reefs, either solitarily or in small aggregations among large corals or in channels.