Distinguished from congeners in British Isles by having olive to orange patch on upper part of opercle in several populations. Differs also by the combination of the following characters: lower jaw extending beyond posterior margin of eye in males larger than 20 cm SL; body dark brown to bluish grey, with orange to red belly in adult males; small orange dots on sides, mostly below lateral line; pelvic, pectoral and anal fins with a conspicuous white anterior margin; and caudal fin with a whitish to orangish margin (Ref. 59043).