Anoplocapros amygdaloides
Boxy, slow-swimming and easy to overlook: find Western Smooth Boxfish year-round on temperate reefs across Western Australia, 16.8-22C water.
Boxy, rigid body encased in a fused bony shell rather than scales, giving it an almost angular, wind-up-toy shape as it hovers over the reef. Adults run to about 21cm and show a smooth grey-brown to olive tone with fine darker speckling, not the bold spots or bright colour of tropical boxfish relatives. Fins are small and set well back, so it seems to paddle rather than swim, with no dramatic colour change between sexes noted in sightings.
Divers typically find it moving slowly and low over reef structure, unhurried and unbothered by close approach thanks to that armoured body offering it real protection. It tends to stick near rock and reef cover rather than open water, and its stiff, paddling swim style makes it easy to pick out once you know the shape to look for.
That boxy shell is made of fused bony plates rather than scales, which is why boxfish swim with such a stiff, deliberate paddling motion instead of the fluid S-curve most fish use.
Sightings show no detected seasonal pattern, and the observed temperature range of 16.8 to 22C spans WA's cooler-water diving conditions across most of the year, so it's reasonable to look for it on any visit.
Reef neighbours a diver could mistake it for. Use the identification notes above to tell them apart.
This one is a Western Australia specialty: every logged sighting in the data comes from Australian waters, concentrated in Western Australia. If you're diving temperate reefs and rocky ledges along the WA coast, it's a realistic uncommon-to-common find rather than a rarity.
Mapping where Western Smooth Boxfish is logged…
They're most reliably found on temperate reefs in Western Australia, which accounts for essentially all logged sightings of this species. Look for them on rocky reef and ledge habitat rather than open sand or tropical coral.
There's no strong seasonal pattern in the sightings, and they're recorded across a water temperature range of 16.8 to 22C, so they're a realistic year-round find on WA reef dives.
Look for a small, rigid, box-shaped body around 21cm long, grey-brown with fine speckling, moving with a stiff paddling motion low over the reef. The fused bony shell and slow, deliberate swimming set it apart from ordinary fin-shaped reef fish.
They typically reach around 21cm in length, a compact, boxy size that keeps them easy to overlook against rock and reef.
Its body is encased in a rigid shell of fused bony plates rather than flexible scales, which is why it swims with a stiff, paddle-like motion instead of a normal fish's side-to-side swimming style.
No, they pose no threat to divers. They're slow, armoured and generally unbothered by divers approaching at a reasonable distance.
Site and sighting data is aggregated from diver logs, iNaturalist and GBIF. For taxonomy and conservation status:
Soldierfish
3,621 sites
