Parma mccullochi
A chocolate-brown damsel with a pale tail, most reliably found on reefs across Western Australia in 16 to 22C water year-round.
Chunky, oval-bodied damselfish around 14 cm, deep chocolate-brown to almost black over most of the body. The tail fin is pale, often near-white, giving a sharp two-tone look against the darker body. It sits with a slightly humped back and holds a stubborn, hovering posture over a patch of reef rather than darting into cover.
Divers usually find it holding station over a patch of reef or rock, defending a patch of algae or eggs rather than schooling or wandering. It is not particularly shy and will often stay put and watch rather than flee when a diver approaches, though it rarely comes close. Most logs describe it as an uncommon but steady find rather than something you have to hunt for on a good WA reef dive.
Like other Parma damselfish, males are thought to guard and tend a patch of algae as a nesting territory, chasing off intruders that stray too close, so a scalyfin holding firm over one spot of reef is likely defending real estate rather than just resting.
Sightings show no clear seasonal pattern, and the water-temperature range logged for this species (16.3 to 22.3C) spans WA's cooler and warmer months, so it is a fair bet on any dive through the year.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
This one is a Western Australia specialty, logged consistently across reef and rocky-reef sites through the region, with sightings concentrated there rather than spread across other states or countries. If you are diving temperate WA sites, it is one of the more dependable damsels to tick off, though usually in ones and twos rather than in numbers.
Mapping where McCulloch's Scalyfin is logged…
It is essentially a Western Australia species for divers, turning up across a wide spread of reef sites there. Outside WA it is not a species you can reliably plan a dive around.
There is no strong season in the sighting data, and it has been logged in water from 16.3 to 22.3C, so it is a reasonable find on WA reef dives at any time of year.
Look for a dark brown, almost black damselfish about 14 cm long with a distinctly pale tail fin. It usually hovers close over one patch of reef rather than schooling, which helps separate it from more mobile damsels.
They grow to around 14 cm, a solid, chunky size for a damselfish, noticeably bulkier than many tropical clownfish and small reef damsels.
No. It poses no danger to divers and will typically just hold its ground or move off slightly if you get close.
Like other Parma damselfish, it likely tends and defends a small algae patch on the reef as a territory, so seeing one holding fast over the same spot dive after dive is not a coincidence.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Yellowtail Clownfish
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