A swimming cube. The body is a rigid shell of fused hexagonal plates with holes cut for the eyes, mouth, fins and tail, so nothing about the fish bends: it moves by sculling with small fins while the body stays perfectly still. Juveniles are bright yellow dice with black spots; adults grow to 45 cm (18 in) and fade to olive with pale-centered spots.
The armor is the trade. It cannot flex, cannot accelerate and cannot hide, and in exchange it is very hard to bite and nearly impossible to swallow. Boxfish spend their days hovering in the open where other fish of their size would not last an hour.
The backup is chemical. Stressed or dying, the skin releases ostracitoxin, a soapy compound that damages the gills of other fish and can kill everything in a confined volume - a well-known way to lose an entire aquarium overnight. In open water it does nothing to a diver.
Feeding is done by blowing. The fish directs a jet of water at the sand to uncover worms and small crustaceans, then picks them off - the same trick the cowfishes use, in a shape even less suited to chasing anything.
The species. Ostracion cubicum Linnaeus 1758 - cubic. ETYFish
- rigid box-shaped body with a squared cross-section, fins working like propellers
- juveniles bright yellow with black dots, adults duller with pale-centered spots
- no scales - a shell of fused plates with holes for the eyes, mouth and fins
- length up to 45 cm
Why it's threatened
There are no known major threats to Ostracion cubicus in the Persian Gulf.
Threat classification from the IUCN Red List.
