Blackstreak Bream

One dark line along the back is the whole identification. It begins under the third or fourth dorsal spine, runs above the lateral line, and stops at the tail stalk: narrow, brown to black, set against an olive green upper body that pales to white below. A thin whitish stripe follows the base of the dorsal fin just above it. On the head a bright blue line runs from the eye forward to the upper jaw, and a second runs back from the eye to the pectoral fin base and finishes in a blue spot.

Its family splits cleanly in two. The threadfin breams proper, the genus Nemipterus, are trawl fish of open sand and mud, hauled up in bulk and named for the filament drawn out of the upper lobe of the tail. The monocle breams, Scolopsis, live on and around reefs and are what a diver sees. This one is a Scolopsis that lives at the depth where the two habits meet, and that is the honest reason you are unlikely to find it.

FishBase puts it between 20 and 50 m. The regional guide illustrates it with a photograph taken outside this sea, which says something about how often it is met on a 🌊 Red Sea dive. It is a western 🌊 Indian Ocean fish: the 🌊 Red Sea, the 🌊 Gulf of Aden, the 🌊 Gulf of Oman, the 🌊 Persian Gulf, the Arabian Sea and the Gulf of Mannar off 🇱🇰 Sri Lanka.

The genus mark is a small spine on the bone under the eye. In this species there is no forward-pointing one, the lower arm of the gill cover is scaly, the head scales run forward to the front of the eyes, and the pelvic fins reach back to the vent. Those characters are what separate it from the other Scolopsis of this region, and they are also why its name has been a mess: earlier authors published this fish as Scolopsis vosmeri and as Scolopsis frenatus.

It reaches 36 cm, with 20 cm ordinary, and takes bottom animals off sand and rubble at the foot of the reef.