Pomatoschistus marmoratus
A pocket-sized goby of sandy lagoons in Sardinia, Murcia and the French Riviera, active year-round in cool 10-17C water.
A stubby little fish barely 6 cm long, mottled in brown, grey and sandy tones that break its outline against the seabed. It sits propped on its fused pelvic fins rather than swimming freely, and the blotchy marbled pattern down its flanks is the main thing to key on. Look for it hovering just above sand or fine sediment rather than on rock or reef structure.
Look for it perched motionless on sand or silty patches close to the seabed, propped up on its pelvic fins rather than actively swimming about. It tends to stay put as divers approach, relying on its mottled camouflage rather than fleeing, which makes it easy to swim straight past if you are not scanning the sand closely. Most sightings come from shallower, sheltered lagoon-type terrain rather than open reef or rock.
Like other members of the sand goby group, it lacks a swim bladder, which is why it rests directly on the bottom instead of hovering in midwater.
Sightings show no clear seasonal pattern, so treat this as a year-round fish, consistent with the cool 10.3 to 17.3C water it is logged in across the season.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged along the Mediterranean coasts of France, Italy and Spain, with strong numbers out of Sardinia in Italy and Murcia in Spain. The French Riviera & Provence and Occitanie also turn up frequent sightings, with smaller pockets in Catalonia and Corsica.
Mapping where Marbled Goby is logged…
It is most often logged in the Mediterranean, especially around Sardinia in Italy, Murcia in Spain, and the French Riviera, Provence and Occitanie coasts of France. Look for sandy or silty patches in sheltered, shallow water rather than rocky reef.
Sightings are spread across the year with no strong seasonal peak, so any time you are diving its Mediterranean sand habitats in the 10 to 17C range should give you a chance.
Look for a tiny, 6 cm fish with a blotchy brown-and-grey marbled pattern, propped motionless on sand rather than swimming in open water. It blends heavily with the seabed, so slow, close scanning is the trick to spotting one.
They typically reach around 6 cm, making them one of the smaller gobies divers encounter on Mediterranean sand and lagoon bottoms.
No, they pose no threat to divers. They are small, sedentary fish that simply sit on the sand and are best left undisturbed for a closer look.
Like related sand gobies, it has no swim bladder, so instead of hovering in the water column it rests directly on the seabed, propped up on its pelvic fins.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Slender Goby
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