Epinephelus ongus
Small reef grouper found on deep drop-offs from Koh Lipe to Raja Ampat, most reliably in the 24.5-28.6C zone below 20m year-round.
A small, stocky grouper reaching around 28cm, easy to overlook against rubble and coral rock. Body is pale brown to grey with fine white to pale streaks running along the flanks, giving it a washed-out, mottled look rather than bold spots or bars. It typically sits still on or near the substrate rather than hovering in open water, which is often the first clue to its identity.
Usually spotted resting motionless on rubble, ledges, or coral rock rather than swimming in the open, often tucked where the reef slope drops toward its 20 to 60m depth range. It is not a fish that follows divers or reacts much to a slow approach, making a careful scan of the bottom the best way to pick it out. Like most groupers it is an ambush feeder, so long stationary spells between short bursts of activity are typical.
Its washed-out streaked pattern works as camouflage against rubble and broken coral, which is likely why it is logged as uncommon at most sites rather than rare, divers simply swim past it.
No clear seasonal pattern shows up in the data, and its comfort range of 24.5 to 28.6C covers tropical reef conditions year-round, so it is a fair bet on any dive in its range regardless of month.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged in Indonesia and Thailand, with Koh Lipe standing out as a strong single region, alongside the Visayas in the Philippines and Nusa Tenggara and Bali in Indonesia. Smaller but consistent numbers come from West Papua and Raja Ampat in Indonesia, Taveuni in Fiji, and Nouméa in New Caledonia.
Mapping where White-streaked Grouper is logged…
Best chances are in Indonesia and Thailand, especially around Koh Lipe, the Visayas in the Philippines, and Nusa Tenggara and Bali in Indonesia. Smaller populations turn up in West Papua, Raja Ampat, Taveuni in Fiji, and Nouméa in New Caledonia.
There is no strong seasonal pattern in the sightings data. It sits comfortably in 24.5 to 28.6C water, so it is present on tropical reefs across the year.
Look for a small, stocky grouper around 28cm with a pale, mottled body marked by fine white streaks along the sides. It is usually found resting still on rubble or reef rock rather than swimming in open water.
They stay small for a grouper, typically around 28cm, which combined with their pale streaked camouflage makes them easy to miss on the reef.
No, they pose no danger to divers. They are a small, non-aggressive reef fish that tends to hold still rather than react to divers nearby.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Blacktip Grouper
2,734 sites
