Pterocaesio trilineata
Silvery fusilier schools logged across Queensland reefs and Taveuni, Fiji, in warm 25-29C water year-round.
Slender, cigar-shaped body around 14 cm long, silvery-blue overall with three dark horizontal stripes running along the flanks toward a forked tail. Usually seen in loose schools hanging just off the reef, picking plankton from the water column rather than grazing the reef itself. The stripes and slim profile are the quickest tell against bulkier reef fish sharing the same water.
Look for it hovering in loose, drifting schools over reef slopes and drop-offs, picking plankton out of the current rather than feeding off the substrate. Schools tend to hold their position over a reef feature and part around divers rather than scattering, making them easy to swim through slowly for photos. Most sightings are along open water above coral rather than tucked into crevices.
Like other fusiliers, it feeds almost entirely in open water on drifting plankton, which is why you find it hanging above the reef rather than nosing around coral heads like most snapper relatives.
No clear seasonal pattern shows up in the sightings, and with a comfortable range of 25.4 to 29.3C it is present on these tropical reefs all year round. Plan around good visibility and calm conditions at your chosen site rather than a particular month.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged on reefs in Queensland, Australia, and around Taveuni, Fiji, with further sightings around Viti Levu and Nouméa in New Caledonia. It turns up as an uncommon find at most sites where it is seen, though a handful of spots in these regions report it as a common, easy-to-spot school.
Mapping where Three-striped Fusilier is logged…
Queensland, Australia, and Taveuni, Fiji, are the strongest areas for sightings, with additional records from Viti Levu, Fiji, and Nouméa, New Caledonia. It's usually an uncommon sighting rather than guaranteed at any single site.
There's no detected seasonal pattern, so it's considered a year-round sighting on these tropical reefs. Warm water between roughly 25 and 29C suits it at any time of year.
Look for a slim, silvery-blue fish around 14 cm long with three dark stripes running along its body and a forked tail. It's usually seen schooling in open water just off the reef rather than resting on the bottom.
They typically reach around 14 cm, making them one of the smaller schooling fish you'll see hovering over reef slopes.
No, they pose no danger to divers. They're plankton feeders that school peacefully in open water and simply part around passing divers.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Emperor
2,055 sites
