Pomacentrus similis
Small blue-grey damselfish common on reefs at Koh Phi Phi and Hikkaduwa, seen year-round in warm 28-29C water.
A small, deep-bodied damselfish that tops out around 5 cm, so it reads as a quick grey-blue blur darting near reef structure. Body colour is a fairly plain pale blue-grey with a faint darker shading along the back, lacking any bold stripe, bar, or eye spot that would make it stand out. The unremarkable, understated look is actually the key clue: if a small damsel on the reef seems to have no strong markings at all, this is a likely candidate.
Expect to find it hovering low over reef rubble and coral heads, sticking close to cover rather than venturing into open water. It's a shy, small-scale presence, usually seen singly or in loose company with other damselfish rather than schooling tightly, and it tends to dart back into the reef structure if you get too close. Most sightings come from reef flat and slope habitat during normal daytime dives rather than any particular time window.
Like most Pomacentrus damselfish, it likely holds a small feeding territory on the reef and will defend it against other small fish, though its plain colouring makes it far less conspicuous doing so than its bolder cousins.
No clear seasonal pattern shows up in the sightings, and with water sitting between 28.1 and 29.4C year-round at these sites, it's a reef fixture in any month you visit.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged around Koh Phi Phi and Phuket in Thailand, and it also turns up steadily at Hikkaduwa in Sri Lanka. A single logged sighting from Karnataka, India, suggests it may range further along the Indian coast than the dive data currently shows, but Thailand and Sri Lanka are the places to plan around.
Mapping where Similar Damselfish is logged…
It's most commonly logged around Koh Phi Phi and Phuket in Thailand, with a strong presence at Hikkaduwa in Sri Lanka as well. A single sighting from Karnataka, India hints at a wider range.
There's no detected season in the sighting data, and it's found in consistently warm water between 28 and 29 C, so it's present on these reefs all year round.
Look for a small, plain blue-grey damselfish around 5 cm long with no bold stripes, bars, or eye spots. Its lack of strong markings, compared to more boldly patterned damselfish, is itself the identifying feature.
They stay small, reaching around 5 cm in length, typical for reef damselfish in the Pomacentrus genus.
No. They pose no threat to divers and simply retreat into reef structure if approached too closely.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Yellowtail Clownfish
3,523 sites
