Craterognathus plagiotaenia
Reef-loving jack found on Queensland and Micronesian reefs in warm 22-28C water, year-round but always uncommon.
Compact silvery jack around 35 cm, deeper-bodied than most trevally species, with a dark diagonal bar or blotch on the cheek just behind the eye that gives it its name. Body tapers to a forked tail typical of the jack family, and the flanks usually show a faint pale-gold wash rather than the flat chrome look of open-water trevally. It swims with the quick, purposeful glide typical of reef jacks rather than the loose schooling drift of open-water species.
Usually spotted cruising alone or in small loose groups over reef slopes and drop-offs rather than schooling in open water like many of its relatives. Divers report it holding a fairly steady course along the reef edge, unbothered by bubbles but not especially approachable either, more a fish you notice passing than one that lingers to inspect you.
It's logged as uncommon at every site where it appears, so unlike bigger schooling trevally species this one tends to be a single memorable sighting rather than a guaranteed encounter.
No clear seasonal pattern shows up in the sightings data, and its comfort range of 22.2 to 28.5C spans typical tropical reef conditions year-round, so any month is fair game at the sites above.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged on reefs off Queensland, Australia, which accounts for the bulk of recorded sightings, with additional pockets in Pohnpei and Chuuk Lagoon in Micronesia. Indonesian reefs in Nusa Tenggara and Sulawesi, plus the Visayas in the Philippines, also turn up occasional sightings, so it's a fish worth watching for anywhere on Indo-Pacific reef structure.
Mapping where Barcheek Trevally is logged…
Queensland, Australia has the strongest run of sightings, with further records from Pohnpei and Chuuk Lagoon in Micronesia, and scattered sightings across Nusa Tenggara and Sulawesi in Indonesia and the Visayas in the Philippines.
There's no detected seasonal pattern, and its warm-water niche of roughly 22 to 28C covers typical tropical reef temperatures all year, so sightings can happen in any month.
Look for a silvery, deep-bodied jack around 35 cm with a dark diagonal cheek bar behind the eye. It moves with a direct, gliding swim over reef structure rather than schooling in open water.
They typically reach around 35 cm, making them a smaller, more compact species than open-water trevally like Giant Trevally.
No, they pose no danger to divers and are simply a reef fish to watch pass by rather than something to be cautious around.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Rainbow Runners
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