Body deep and very compressed. Small head with pointed snout. Small protractile slightly oblique mouth. Long and narrow tightly packed teeth forming brush-like surface at the anterior of both jaws. Large eye and narrow interorbital distance. A long continuous dorsal fin with clear incisions between its 7th-8th spines. The posterior part of dorsal and anal fins is elongated giving the entire fish a triangular shape. Caudal fin round. Body covered with finely ctenoid scales including on the head and some of the median fins membranes.
color : the anterior part of the head from the dorsal fin origin, behind the eye to pelvic fin origin brownish-orange. Most of the body bluish-grey with narrow chevron-shaped vertical yellow lines. Posterior part of dorsal fin, caudal peduncle and most of the caudal fin are black. Posterior edge of caudal fin light blue to white.
size : common 8-12 cm (max. 15 cm).
The color pattern of this species differs significantly from all other Mediterranean species.
BIOLOGY / ECOLOGY
Live mainly in pairs but in areas with poor coral reefs, such as in the Gulf of Suez where it forms aggregations of 40-50 fish. Feeds primary on coral polyps and benthic invertebrates in its native region. Eggs and larvae pelagic. The late post-larvae, often called tholichthys, bear large bony plates on the head and anterior part of the body.
habitat : among coral reefs, rocky and open habitats at depths down to 40 m.