Scolopsis bilineata, the two-lined monocle bream, bridled monocle bream, bridled spinecheek, double-lined coral bream or yellow-finned spine-cheek, is a species of marine ray-finned fish belonging to the family Nemipteridae, the threadfin breams. This species is found in the to the Indian and Western Pacific Oceans.
Scolopsis bilineata was first formally described as Anthias bilineatus by the German physician and naturalist Marcus Elieser Bloch in 1793 with its type locality given as Japan. The 5th edition of Fishes of the World classifies the genus Scolopsis within the family Nemipteridae which it places in the order Spariformes.[1]
Scolopsis bilineata has the specific name bilineata which means "two lined", a reference to its the two curved, prarllel dark stripes on the head of adults.[2]
Scolopsis bilineata has its dorsal fin supported by 10 spines and 7 soft rays while the anal fin contains 3 spines and 7 soft rays. Its body has a depth that fits into its standard length between 2.5 and 3 times with the length of the snout being less than the diameter of the eye. The scales on the head reach forward as far as or beyond the front nostrils and there are scales on the lower limb of the preoperculum. There is a forward pointing spine on the suborbital. The pelvic fins are long, extending to or nearly to the level of the origin of the anal fin. The caudal fin is forked.[3] There is white stripe with black margins that arcs upwards from underneath the eye to the centre of the base of the dorsal fin. There is a pair of white lines over and to the rear of the eyes. The spiny part of the dorsal fin is yellow and there is a white area on the back underneath the soft-rayed part of the dorsal fin.[4] In the juveniles the upper half of body is black with two yellow stripes and the middle of the flanks have a wide poorly defined white stripe with a black mark on the anal fin.[5] This species has a maximum published total length of although standard length is more typical.
Scolopsis bilineata is found in the eastern Indian Ocean and the western Pacific Ocean. It ranges from the Maldives and Sri Lanka east as far as Fiji and the Caroline Islands, it has also been reported from Tonga. Its range extends north to the Ryukyu Islands and south to Australia. Its Australian range extends from the Houtman Abrolhos in ]Western Australia along the western, northern and eastern coasts as far as Sydney in New South Wales. It has also been recorded from the Rowley Shoals and Scott Reef off Western Australia, the Ashmore Reef in the Timor Sea, Christmas Island, Cocos (Keeling) Islands, Elizabeth and Middleton Reefs Marine National Park Reserve and Lord Howe Island.[5] It is found at depths between on coral reefs, with the juveniles being found inshore, in lagoons or in areas of rubble.
Scolopsis bilineata are found typically either as solitary individuals or in pairs, frequently gather in small groups. Its prey is mainly benthic invertebrates and smaller fishes. It is a protogynous hermaphrodite but there is no evidence that this is functional and the sex change occur prior to sexual maturation. The juveniles are Batesian mimics of the linespot fangblenny (Meiacanthus grammistes), a species armed with venomous canin-like teeth.[5]
The two-lined monocle bream exhibits biofluorescence, that is, when illuminated by blue or ultraviolet light, it re-emits it as green, and appears differently than under white light illumination (only stripes on the upper front part are visible). Biofluorescence may assist in intraspecific communication and camouflage, blending the fish with green-fluorescing Acropora corals.[6]
Scolpsis bilineata is occasionally found in small numbers in fuish markets and there is no fishery specifically tageting this species. In the Philippines this species is caught to be sold in the aquarium trade.