Chaetodermis penicilligerus
Spot this camouflaged filefish among the reefs of Western Australia and Malaysia's east coast, where it hides in plain sight year-round.
Grows to around 22 cm and looks like a piece of drifting seaweed more than a fish, thanks to the branching skin flaps (dermal filaments) covering its flattened, oval body. Colour runs mottled brown, green or grey, shifting to match whatever reef debris or algae it's parked next to. Look for the small mouth, a single thin dorsal spine near the head, and a body that seems to sway rather than swim.
Divers usually find it holding still against weedy or rubble-strewn bottoms, relying on its shaggy camouflage rather than speed to avoid attention. It tends to drift or hover with slow, almost hesitant fin movements that mimic swaying algae, and it will often let a diver approach closely before easing away. Most sightings are solitary animals tucked close to structure rather than out in open water.
Those branching skin flaps aren't just decoration, they let it disappear against weed and algae-covered rubble so effectively that most divers who log it describe finding it by accident rather than searching it out.
No clear season shows up in the sightings, and with a comfort range of about 24 to 29 C it's a year-round resident of the reefs it favours rather than a seasonal visitor.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
Most reliably logged in Western Australia, with a strong second population along Malaysia's east coast in Peninsular Malaysia. Smaller numbers turn up at Longdong in Taiwan and in Bali, Indonesia, but sightings everywhere tend to be uncommon to rare rather than a sure thing.
Mapping where Tasselled Leatherjacket is logged…
Western Australia is the strongest area for sightings, followed by Malaysia's east coast. Smaller numbers of dives log it at Longdong in Taiwan and in Bali, Indonesia.
There's no detected seasonal pattern, and it sits comfortably in 24 to 29 C water, so it's found on suitable reefs throughout the year rather than during a particular month.
Look for a small, flattened fish around 22 cm covered in shaggy, branching skin flaps that make it look like floating weed. Its mottled brown-green colouring and slow swaying motion near the bottom are the giveaways.
They reach about 22 cm in length, making them a small, easy-to-overlook fish on the reef.
Yes, rather than fleeing, it relies on its weed-like skin flaps and slow, swaying movement to blend into algae and rubble, often going unnoticed by both predators and divers until it's pointed out.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Whitespotted Filefish
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