Takes sand by the mouthful and sieves it out through the gills, working in pairs.
A stocky, blunt-headed goby reaching about 15 cm, pale grey-green to fawn with five broad dark bars running down the flank and a scatter of small blue and orange dots over the head and cheeks. There is a dark spot at the upper base of the tail fin, and the two dorsal fins are rounded and carry rows of spots rather than any filament. The pattern is the point of confusion: Amblygobius nocturnus is smaller, reaches about 9 cm and has narrower, more numerous bars; Amblygobius decussatus is marked with orange lengthwise stripes rather than bars; and the Valenciennea sleeper gobies, which share the habitat and the sand-sifting habit, are marked with lines and dashes running along the body and have a more pointed head.
Feeds by taking a mouthful of sand, sorting small crustaceans, worms and organic material inside the mouth and expelling the cleaned grains through the gill openings in a small plume. It also grazes filamentous algae. Almost always in pairs, which share a burrow excavated under a rock or a lump of rubble and reinforced with shell fragments; both animals bolt into it together and reappear within a minute or two. Recorded from about 2 to 25 m on sand and rubble, generally in the shallower half of a muck slope and often where sand meets seagrass or a low reef edge. It is common enough at most of these destinations to be passed over, and it is one of the easier fish on which to watch the sand-sifting behaviour at close range, because the pair returns to the same burrow entrance each time.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.
