Plectroglyphidodon apicalis
A small dusky damselfish logged across Queensland reefs, from the GBR to inshore bommies, in warm 24-28C water year-round.
A compact, oval-bodied damselfish that rarely tops 10 cm, seen in shades of dusky brown to near-black with a faint pale rim along the tail and dorsal fin. It has the typical deep, laterally flattened damselfish silhouette and swims in short, jerky bursts rather than gliding. There's no strong pattern to key on, so location on the reef and its plain dark colouring are usually the best clues.
Usually seen holding a small patch of reef or rubble, darting out to feed on algae and drifting plankton before ducking back to cover. It's not especially bold or skittish around divers, more likely to just carry on with its patch-defending business a few feet away. Most sightings are logged as uncommon rather than abundant, so it's a fish you notice individually rather than in a crowd.
Like most damselfish, it will chase off other fish and even divers that linger too close to its patch of algae, a defensive habit that's disproportionate to its 10 cm size.
Sighting data doesn't show a clear season, and with a comfortable range of 24.4 to 28.3C, it's likely on Queensland reefs all year round. Plan around good Great Barrier Reef diving conditions generally rather than chasing a specific month for this fish.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Almost every logged sighting comes from Queensland, Australia, making the Great Barrier Reef and its inshore and offshore bommies the reliable place to find it. A single site in New South Wales shows it can turn up further south too, but Queensland is where divers consistently log this one.
Mapping where Australian Gregory is logged…
Queensland, Australia is by far the most reliable place, with sightings spread across Great Barrier Reef dive sites. A rare sighting has also been logged in New South Wales.
There's no strong seasonal pattern in the sighting data, and its 24.4 to 28.3C temperature range is typical of Queensland reefs year-round, so any time you're diving there works.
Look for a small, dark brown to blackish damselfish around 10 cm long with a faint pale edge to the tail and dorsal fin. It has the classic deep-bodied damselfish shape and moves in quick, darting bursts near a small patch of reef.
They max out at around 10 cm, making them one of the smaller damselfish you'll see on Queensland reefs.
No, they pose no danger to divers. They may dart towards you if you get close to their patch of reef, but this is just territorial bluffing, not a 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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