Mahidolia mystacina
A tiny shrimp-partnered goby logged on sandy slopes in Queensland and Sulawesi, in warm 26-29C water year-round.
A slender 6 cm goby that perches upright on fins near a burrow opening rather than swimming freely over the reef. Look for a pale, semi-translucent body with fine dark speckling and a tall, flag-like first dorsal fin that it flicks upright when alert. Males typically carry a more elongated, filamentous dorsal spine than females, giving the fin its flag shape.
Spend most of a sighting watching one hover just above its burrow mouth, sharing the hole with a burrowing shrimp that keeps the tunnel clear of sand. The goby stays close to the entrance and darts in the instant it senses a shadow or fast movement, so a slow approach and settling on the sand a body-length away gives the best look. Divers most often find it on open sand or rubble patches rather than on coral itself, usually in daylight hours.
It lives in an obligate partnership with a burrowing alpheid shrimp: the shrimp digs and maintains the shared tunnel while the goby, with far better eyesight, keeps watch and signals danger with a flick of its tail.
Comfortable across a 25.9 to 29.1C range, and the data shows no clear seasonal pattern, so it turns up on tropical sand slopes throughout the year.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most often logged on sandy and rubble slopes in Queensland, Australia, with additional sightings from Sulawesi, Indonesia and Dili, Timor-Leste. Sightings across all three countries are on the sparse side, so it's a species you find by working sand patches carefully rather than one you stumble on by chance.
Mapping where Flagfin Prawn Goby is logged…
It's most reliably reported from Queensland in Australia, with further sightings from Sulawesi in Indonesia and around Dili in Timor-Leste. Look for it on sandy or rubble slopes rather than coral heads.
There's no strong seasonal signal in the sightings data, and it tolerates a warm 25.9 to 29.1C range, so it can be found on tropical sand slopes at any time of year.
Look for a small, pale, speckled goby around 6 cm long hovering upright over a burrow entrance in sand, with a tall flag-like dorsal fin it raises when alert. It rarely strays far from its burrow, usually shared with a shrimp.
They reach around 6 cm in length, making them one of the smaller reef gobies divers spot on sand slopes.
Flagfin prawn gobies share a burrow with an alpheid shrimp that digs and maintains the tunnel while nearly blind. In return, the sharp-eyed goby watches for predators and signals danger, letting both retreat together.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Slender Goby
803 sites
