Pomacentrus caeruleus
Small blue damselfish common across Seychelles' Inner Islands and the Maldives' Central Atolls, in warm 25-29C reef water year-round.
A small, slender damselfish around 7cm, glowing an even electric to deep blue over most of the body with fins tinted the same colour. There's no bold contrasting patch or bar to key on, so look at the overall uniform blue wash and the slightly darker shading toward the tail as the main giveaway. It moves in quick, short bursts rather than gliding, which helps separate it from similarly blue reef fish at a glance.
Usually seen hovering low over coral rubble, sand patches or reef bases in small loose groups, picking at plankton drifting past rather than feeding directly off the substrate. It holds its ground fairly well as divers approach, darting for cover into nearby crevices only when pressed rather than fleeing outright. Most sightings are during daylight hours on shallow to mid-depth reef, where it's logged as uncommon at the majority of sites and common at a solid minority.
Like most damselfish, it likely spawns demersal eggs laid on a cleared patch of substrate that one parent guards and fans until hatching, a common pomacentrid strategy that keeps small numbers concentrated on a single patch of reef.
No clear seasonal pattern shows up in the sightings data, and with a comfortable range of 25 to 29.3C this is a year-round reef resident across its Indian Ocean range. Plan around the diving season for your chosen country rather than the fish itself.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged in the Seychelles, especially around the Inner Islands, and in the Maldives' Central Atolls, where sightings are dense across dozens of sites. Smaller but still solid populations turn up in Mauritius (notably Grand Baie and Coin de Mire) and along the Kenyan coast around Diani, with a single logged site in Reunion.
Mapping where Caerulean Damsel is logged…
The strongest sightings are in the Seychelles' Inner Islands and the Maldives' Central Atolls, with further populations in Mauritius around Grand Baie and Coin de Mire, and along the Kenyan coast near Diani.
There's no detected seasonal pattern, and it tolerates a warm 25 to 29.3C range, so it's present on reefs across its range all year. Time your trip around general diving conditions rather than a specific season for this fish.
Look for a small, slim damselfish around 7cm long with an even, glowing blue body and fins, lacking any bold stripe or bar. It moves in quick short darts over rubble and reef base rather than swimming in smooth open water.
They stay small, reaching around 7cm as adults, which is typical for pomacentrid damselfish.
No, they pose no threat to divers and are simply small reef fish that hold their ground and dart for cover if approached too closely.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Yellowtail Clownfish
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