It eats sand. Not what is lying on the sand, the sand itself: the goby takes a full mouthful, sorts it inside, swallows the worms, crustaceans and organic scraps, and blows the cleaned grains back out through the gill openings in a small cloud. Then it does it again, and again, all day.
A pair working one patch turns over a remarkable amount of seabed that way, and sand-sifting gobies are part of the reason sediment around a reef stays turned and aerated instead of going stagnant.
They live in pairs and the pairing holds. Two fish share one burrow dug under a rock or a slab of rubble, excavated mouthful by mouthful the same way they feed, and they hover a few centimeters above the entrance where they can drop into it the moment anything approaches.
The sexes are marked differently, which is unusual enough in gobies to be useful: the male carries three dark spots at the base of the second dorsal fin, the female a brown-edged band running from her upper lip to the top of the gill cover.
The genus. Amblygobius Bleeker 1874 - amblýs (blunt). ETYFish
The species. Amblygobius albimaculatus (Rüppell 1830) - albus (white) + maculatus (spotted). ETYFish
- hovers just above the sand, almost always in pairs
- takes mouthfuls of sand and blows the cleaned grains out through the gill covers
- males with three dark spots at the base of the second dorsal fin
- females with a brown-edged band from the upper lip to the gill cover
- up to 18 cm
