Ferdauia ferdau
Spot banded trevally on reefs in Palau's Rock Islands or Bali; uncommon but reliable in 24.7-29.1 C water year-round.
Silvery-grey body deepening to a slightly flattened, oval profile typical of jacks, growing to around 49 cm. Look for faint dark vertical bars along the flanks, which fade in and out depending on the fish's mood and can be hard to see at a distance. The blunt head, forked tail, and steady mid-water cruising posture set it apart from more slender jacks.
Usually seen cruising alone or in small loose groups over reef slopes and drop-offs rather than schooling tightly like some of its relatives. It tends to keep a comfortable distance from divers, patrolling mid-water or hovering near structure while hunting smaller reef fish. Sightings are often brief, a quick pass along a wall before it moves back into open water.
Like other trevallies, it hunts by ambush, using sudden bursts of speed to run down smaller fish rather than chasing prey over long distances.
No clear seasonal pattern shows up in the data, and with a comfortable range of 24.7 to 29.1 C it's present on tropical reefs throughout the year. Treat any dive at the sites above as a fair chance, not a seasonal bet.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged around Palau's Rock Islands and Bali in Indonesia, with a solid presence off Palawan in the Philippines. Divers also report it around Muscat in Oman, in the Maldives' Central Atolls, and at Kwajalein Atoll in the Marshall Islands, though everywhere it turns up it's an uncommon rather than guaranteed sighting.
Mapping where Banded Trevally is logged…
Palau's Rock Islands and Bali in Indonesia are the most consistent spots, with further sightings off Palawan in the Philippines, Muscat in Oman, the Maldives' Central Atolls, and Kwajalein Atoll in the Marshall Islands.
There's no strong season in the data, so it's a year-round possibility on the reefs where it occurs, thanks to its comfortable range of roughly 25 to 29 C.
Look for a silvery, oval-bodied jack around 49 cm with faint dark vertical bars on the flanks that can flicker in and out of visibility. It cruises steadily in open water or along reef edges rather than darting erratically.
They typically reach around 49 cm in length, a medium-sized member of the jack family, noticeably smaller than giant trevally.
No, they're not considered dangerous to divers. They keep their distance and show no aggressive behaviour, simply cruising past on the reef.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Rainbow Runners
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