A porcupinefish with long spines and dark blotches, under ledges by day and out over sand at night.
To about 50 or 60 cm depending on the source, but commonly 15, so most individuals a diver sees are far smaller than the maximum. A robust inflatable oval body with a wide blunt head and very large eyes, often with green-gold flecking in the iris. Light olive to pale brown above and white below, with a large brown bar running from above to below the eye, a brown bar over the back of the head, dark blotches across the back and small black spots on the upper head and body. The spines are long, the ones on the snout longer than those on the body, and there are none on the base of the tail.
The porcupinefish is the constant confusion and there is a two-part check. This fish has long spines, dark blotches and bars, and no spots on the fins. The porcupinefish has short spines, fine even spotting that continues onto the fins, and grows to nearly twice the size.
It is nocturnal. By day it shelters in caves, under ledges and among rubble, which is where divers find it, motionless. At night it crushes gastropods, bivalves, sea stars, sea cucumbers, urchins and crabs with its fused beak. It lives typically between 2 and 35 m and has been recorded to about 190.
The flesh and organs contain tetrodotoxin, so it is poisonous to eat, but there is no contact risk at all to a diver: the toxin is a poison, not a venom. The real hazard is the beak, which is powerful. Do not provoke it into inflating for a photograph; inflation is a stress response and can kill the fish if it takes in air at the surface.
Ratings are per location: 1 means found on most dives that look for it, 5 means a handful of records. Where enough dives have been logged the figure is calculated from them; otherwise it is an editorial estimate, and says so. We publish habitat and destination, not the dive site.