Trimma halonevum
A tiny reef goby seen at just a handful of sites in Sulawesi and Luzon, sitting still in warm 27 to 29C water year-round.
Barely 2cm long, this goby is a translucent, almost see-through fish with fine speckled markings that give it a stippled, pimpled look along the body, which is where the common name comes from. It perches rather than swims freely, propped on its front fins on rubble, coral or sponge with its body angled slightly upward. Look closely, since at this size it reads as a pale smudge until you get your mask within a few centimetres of the substrate.
Divers find it parked motionless on rubble patches, coral rock or sponge, propped up on its pectoral fins and barely moving unless disturbed. It doesn't dart for cover the way many small gobies do, but its size and see-through body mean most divers swim straight past without noticing it at all. Best picked out with a slow, close look at the substrate rather than mid-water scanning.
Like other pygmy gobies, it likely lives only a few weeks to a couple of months as an adult, one of the shortest lifespans known in any vertebrate, which helps explain why sightings are so patchy and localised.
There isn't enough logged data to show a clear season, and the water temperature range recorded, 27.1 to 29.0C, is stable tropical warmth all year, so it should be around on the same reefs in any month you visit.
This goby is a rare enough find, logged so far only in Sulawesi in Indonesia and in Luzon in the Philippines. Sulawesi carries the stronger record of the two, with Luzon a secondary spot to check.
Mapping where Pimple Pygmygoby is logged…
Confirmed sightings come from Sulawesi in Indonesia and Luzon in the Philippines, with Sulawesi the stronger of the two for logged records. It's an uncommon find even at these sites, so treat any sighting as a bonus rather than a target.
There's no detected season in the sighting data, and it's recorded in stable warm water between 27.1 and 29.0C, so it appears to be a year-round resident on the reefs where it's found.
Look for a near-transparent fish only about 2cm long, propped on rubble or coral with fine speckled markings across its body. It stays still rather than swimming off, so slow, close scanning of the substrate is the way to spot it.
They max out around 2cm, making them one of the smallest fish you're likely to try to photograph on a reef.
As with other pygmy gobies, it likely has a very short adult lifespan of just weeks to a couple of months, one of the fastest life cycles of any vertebrate.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Slender Goby
803 sites
