Anyperodon leucogrammicus
Elongated grouper with pale stripes, most reliably logged in the Maldives' Central Atolls and Raja Ampat at 25-29 C reefs.
Long, slim-bodied grouper (unusual for the family) growing to around 45cm, patterned with pale grey-green to yellowish stripes running head to tail over a darker base colour. The elongated shape and faint stripe pattern set it apart from the boxier, blotchy groupers most divers know. Scattered small dark spots may show on the head and fins, and it often sits low and still against the reef, blending into dappled light.
Usually spotted parked motionless on or near coral structure, using its slender shape to tuck into crevices and overhangs rather than patrolling open water. It's an ambush hunter, watching for smaller reef fish and crustaceans to wander close before striking, and it tends to hold its position rather than bolt when divers approach slowly. Most sightings come from typical daytime reef dives rather than any obvious dawn or dusk pattern.
Its stretched-out body shape is atypical for groupers, most of which are stocky and deep-bodied; this streamlined build lets it squeeze into narrow reef crevices that bulkier groupers can't access.
No clear seasonal pattern shows in the sightings data, and it sits comfortably in 24.9 to 29 C water, so it's a year-round find on the reefs where it occurs.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most consistently logged in the Maldives, especially the Central Atolls, and in Indonesia's Raja Ampat region, with strong numbers also from Sabah in Malaysia and the Inner Islands of Seychelles. Malaysia's Peninsular East Coast, the Philippines' Palawan, and Khao Lak in Thailand also produce reliable sightings, making this a wide Indo-Pacific reef species rather than a regional specialty.
Mapping where Slender Grouper is logged…
The Maldives (particularly the Central Atolls) and Raja Ampat in Indonesia are the most reliable spots, with good numbers also reported from Sabah in Malaysia, the Seychelles' Inner Islands, and Palawan in the Philippines.
There's no strong season in the sightings data. It lives in water between roughly 25 and 29 C year-round, so any time you're diving its reef habitats gives you a fair chance.
Look for an elongated, slim-bodied grouper around 45cm with pale grey-green stripes over a darker body, usually sitting still near reef structure. The stretched shape is the biggest tell, since most groupers look boxier.
They typically reach around 45cm in length, making them one of the more modestly sized members of the grouper family.
No, they're not considered dangerous to divers. They're calm reef predators that hold still or retreat into crevices rather than react aggressively to divers nearby.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Blacktip Grouper
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