Every one of these fish starts life as a female. Some later become male, and the change runs one way only, which means the large individuals on a reef are mostly males - and fishing that takes the big ones takes the breeding males first.
The breeding runs on the moon. Where it has been studied the season covers a few months, and within it spawning falls in the last days of each lunar month, so the fish gather, spawn on a schedule set by the tidal cycle, and disperse. A patch of reef can hold a crowd of them one week and almost none the next.
What it eats is written in its jaws: the back teeth are rounded and blunt, built for crushing, and it uses them on crustaceans, snails and urchins taken out of sand and rubble beside the reef.
The young grow up somewhere else. They live in seagrass beds and move onto the reef as adults, which ties this fish to two habitats at once and makes it vulnerable wherever seagrass gets dredged or buried.
The stripe in its name is a faint yellow-orange line low on the flank. Obsoletus means worn out, which is a fair description of it.
The species. Lethrinus obsoletus (Forsskål 1775) - worn out or decayed. ETYFish
- light tan to olive body with a faint yellow-orange stripe low on the flank
- indistinct dark bars across the head
- pointed snout with a straight forehead profile
- over sand and rubble beside the reef rather than on it
- up to 60 cm
Why it's threatened
Lethrinus obsoletus is relatively slow growing and late maturing, suggesting a high vulnerability to over-exploitation.
Threat classification from the IUCN Red List.
