Aethaloperca rogaa
Dark, chunky grouper with a red-rimmed mouth, most reliably found on Maldives house reefs and Red Sea drop-offs year-round.
A stocky, dark chocolate-brown to almost black grouper with a squarish head and a give-away bright red or orange lining inside the mouth, visible whenever it gapes or yawns. It grows to around 42 centimetres, sits low against the reef structure rather than hovering, and often has faint darker mottling over the body that only shows under a torch or strobe. There's no strong reported colour split between juveniles and adults, so size and posture near ledges are your other clues.
Expect to find it tucked into reef crevices, under overhangs or against coral bommies rather than out in open water, usually sitting still or moving slowly along the structure. It's logged as uncommon at most sites where divers see it, so a sighting tends to be a single fish holding its ground rather than a shoal, and it generally lets divers get reasonably close before easing back into cover.
That red-orange mouth lining is the fastest field mark on this species and is easiest to spot the moment the fish opens up to breathe or feed, rather than in a closed-mouth profile shot.
No clear seasonal pattern shows up in the sightings, and its comfort range of roughly 24 to 29°C spans most of the diving calendar on these reefs, so plan around the destination's usual dive season rather than a fish-specific window.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
This is very much a Maldives fish first: it turns up across the Central Atolls and Southern Atolls more than anywhere else logged, tucked under ledges on house reefs and channel walls. Outside the Maldives, it's a steady find in the Egyptian Red Sea (Red Sea Riviera and South Sinai) and in Thailand around Khao Lak, with smaller numbers reported from Raja Ampat in Indonesia, Luzon in the Philippines, the Red Sea coast of Saudi Arabia, and Palau.
Mapping where Redmouth Grouper is logged…
Your best odds are in the Maldives, especially the Central and Southern Atolls, where it's logged far more than anywhere else. It's also a reliable sighting in the Egyptian Red Sea and around Khao Lak in Thailand, with occasional records from Raja Ampat, the Philippines, Saudi Arabia and Palau.
There's no detected season for this species, and it tolerates a wide 24 to 29°C range, so it's present on tropical reefs year-round. Time your trip around your destination's general dive season rather than around this fish.
Look for a dark brown to blackish, stocky grouper around 40 centimetres tucked against reef structure, with a bright red-orange mouth lining that flashes when it opens up. It sits low and still near ledges rather than swimming in open water.
They reach around 42 centimetres, making them a mid-sized reef grouper rather than one of the giant grouper species.
No, they're not considered dangerous to divers. They're a calm, reef-associated species that tends to hold near cover rather than approach or confront divers.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Blacktip Grouper
2,734 sites
