Parma occidentalis
A small, feisty damselfish common on Western Australia's temperate reefs, usually seen in 18 to 24 C water.
A stocky, oval-bodied damselfish around 9 cm, mottled brown to grey-brown with faint pale scale edges that give it a scaled, textured look rather than bold stripes or spots. It has a single continuous dorsal fin and a squared-off tail, and it tends to hold a fixed position near a patch of reef rather than schooling openly in the water column. There's no bright colour or high-contrast marking to key on, so body shape and its habit of staying tight to a den or ledge are the more reliable clues underwater.
Divers typically find it holding a patch of reef or a rocky ledge, sitting fairly still or making short darting movements rather than roaming far. Like many damselfish it can get defensive around its patch, nipping toward divers or other fish that linger too close, though it is not a species that causes divers any trouble. Most sightings are of single fish or loose, spaced-out individuals rather than groups.
Many damselfish in this family, including scalyfins, guard a patch of reef as a feeding and breeding territory and will actively chase off intruders many times their own size, so that bold little chase you see near a rock ledge is likely a territorial display rather than aggression toward you.
Sightings show no clear seasonal pattern, and with a comfortable range of 18 to 24.2 C it is around on Western Australia's temperate reefs across the year rather than during one narrow window.
This one is essentially a Western Australia specialty among logged dives, found right along the state's temperate reef and rocky-shore sites. It turns up as an uncommon to common sighting at a wide spread of Western Australian dive sites rather than being concentrated in one or two famous spots, so any well-explored reef in the region is worth checking.
Mapping where Western Scalyfin is logged…
They are most reliably found on temperate reef and rocky-shore dive sites across Western Australia, where they show up as an uncommon to common sighting at a wide range of sites.
There's no strong season in the sightings data, and they tolerate a fairly wide temperate range of 18 to 24 C, so they're a reasonable year-round find on Western Australian reefs.
Look for a small, stocky brown to grey-brown damselfish around 9 cm long with faint pale scale edging rather than bold markings. It usually sits close to a rocky ledge or reef patch rather than swimming openly.
They top out at around 9 cm, making them one of the smaller damselfish you'll see on a Western Australian reef dive.
No. They pose no danger to divers, though like other damselfish they may dart toward you if you get close to their patch of reef.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Yellowtail Clownfish
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