Chrysiptera glauca
Small grey-blue damselfish common at Saint-Leu, Reunion and Flic-en-Flac, Mauritius, in warm 25-29C shallows year-round.
A small, deep-bodied damselfish, around 8 cm, in dull grey to blue-grey with a faint pale patch near the base of the tail. The body is compressed and oval, with a blunt snout and none of the bold stripes or bright yellow seen on flashier damselfish. It often sits close to rubble or short reef structure, angled slightly head-down, making the plain grey colouring the main giveaway against brighter reef fish nearby.
Usually seen hovering or darting around shallow rubble patches and reef edges, sticking close to a home patch rather than roaming. It tends to hold its ground when divers approach, ducking into cover only briefly before returning to feed or patrol, and is most often spotted logged as an uncommon rather than everyday find even on reefs where it turns up.
Like other damselfish, it likely guards a small patch of reef against intruders, a territorial streak common across the family that makes it easy to watch return to the same spot dive after dive.
No clear seasonal pattern shows up in the sightings, and with a comfortable range of 25.1 to 29.3C it's present on these reefs year-round rather than tied to a particular month.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged around Mauritius, especially Flic-en-Flac, Grand Baie and Trou aux Biches, and on Reunion's coast at Saint-Leu, with strong numbers too at Orchid Island in Taiwan and Rarotonga in the Cook Islands. Smaller but consistent sightings turn up at Ponta do Ouro in Mozambique and sites in Japan and Guam, making it a fixture of shallow Indo-Pacific reef diving well beyond any single hotspot.
Mapping where Grey Demoiselle is logged…
Mauritius and Reunion are the strongholds, particularly Flic-en-Flac, Grand Baie, Trou aux Biches and Saint-Leu. It also shows up reliably at Orchid Island in Taiwan, Rarotonga in the Cook Islands, and Ponta do Ouro in Mozambique.
There's no strong season in the sightings, and it tolerates a wide warm range of about 25 to 29C, so it's a year-round find on the reefs where it lives.
Look for a small, oval-bodied damselfish around 8 cm long in plain grey to blue-grey, with a faint pale mark near the tail base and no bold stripes. It usually sits close to rubble or low reef structure rather than swimming in open water.
They stay small, topping out at around 8 cm, typical for damselfish in the Chrysiptera genus.
No, they pose no risk to divers and are simply small territorial reef fish that may dart towards you if you get close to their patch, without any real threat.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Yellowtail Clownfish
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