- English Name : Straited surgeonfish
- Local Name : Rongu dhemi kaalhu
- Size : Max. 26 cm
- Family : ACANTHURIDAE
- Order : Perciformes
- Distinctive Characters: Dorsal fin with 8 spines and 27-31 rays. Anal fin with 3 spines and 24-28 rays. Pectoral rays 16-17. Body depth 1.9-2.3 in standard length. Teeth movable. Caudal fin lunate.
- Colour: Dark brown with blue longitudinal lines on body and orange dots on head. Dark blue bands on dorsal and anal fins.
- Habitat and Biology: Ubiquitous, in various habitats, from protected lagoons to ocean reefs. Occur singly or in small to very large aggregations at depths up to 30 m. Detritus feeder with comb-like teeth.
- Distribution: Indo-Pacific.
- Remarks: Ctenochaetus striatus is one of the most common reef fishes, but because of its dull colouration can easily be overlooked. It is rather similar to C. strigosus (next page) but can be distinguished on the basis of colouration, caudal fin shape and fin counts.