Chromis alpha
Small damselfish most reliably logged around Taveuni, Fiji, in warm 26-29C water year-round on Pacific reefs.
A small damselfish at around 6 cm, easy to overlook in a crowd of reef fish unless you know to look for it. Expect a compact, oval body typical of chromis, held in loose groups just above coral heads rather than tight to the substrate. There is no documented colour split between juveniles and adults in the current data, so size and posture in the water column are your best cues alongside location.
Divers log it as an uncommon find, so it is not a fish you should expect to see on every dive even at its best sites like Taveuni. When present it behaves like a typical reef-associated chromis, hovering in loose aggregations over coral structure and feeding on drifting plankton in the water column rather than picking at the reef itself. It shows little interest in divers and tends to hold station over its patch of reef rather than approach or flee.
Like other chromis, it likely feeds by picking plankton straight out of the current rather than grazing algae, which is why you often see small groups holding position just off the reef rather than sitting on it.
No clear seasonal pattern shows up in the sighting data, and its comfort range of 26 to 29C matches tropical Pacific reefs all year, so any month is a reasonable bet at the sites above.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Taveuni in Fiji is by far the most consistent place to find it, with a run of sites logging sightings there, backed up by other Fijian spots in Lomaiviti. Outside Fiji, it turns up around Tumon Bay and the North and Southern Coasts of Guam, in the Society Islands of French Polynesia, and at a smaller number of sites in Luzon in the Philippines and Peleliu in Palau.
Mapping where Alpha Chromis is logged…
Taveuni in Fiji is the most reliable location, with further sightings around Guam's Tumon Bay and north and south coasts, the Society Islands in French Polynesia, and single sites in Luzon and Palau.
There is no detected season in the sighting data, and its 26 to 29C temperature range holds year-round on the tropical reefs where it is found, so it can turn up on any dive trip to those regions.
Look for a small damselfish, about 6 cm, holding in loose groups above coral structure rather than sitting on the bottom. It lacks any single bold marking, so confirming it usually comes down to size, posture, and location rather than a distinctive pattern.
They stay small, reaching around 6 cm, in line with most other chromis species in the damselfish family.
No. They are a small, harmless reef fish with no defensive or aggressive behaviour reported towards divers.
It is logged as uncommon even at the sites where it does occur, including its Fijian stronghold around Taveuni, so spotting one is a nice bonus rather than a guaranteed sighting.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
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