
Blue-spotted spinefoot
Siganus corallinus
Siganus luridus

The dusky spinefoot is a mid-sized rabbitfish, usually around 20 cm and up to 30 cm long, that grazes reefs by day and carries venomous spines for defence.
Also known as: squaretail rabbitfish
Most rabbitfish have a forked tail, but this one's tail is squared off straight across - the mark behind its other name, the squaretail rabbitfish.
This fish has a flattened, oval body in olive green to dark brown with a mottled pattern that varies between regions. The pectoral fins are pale, almost see-through yellow, and dark bars cross the tail fin, which is cut straight across rather than forked.
It lives over hard bottoms of coral and rocky reef, or rock debris on compacted sand, from East Africa and the Red Sea to Madagascar and the Mascarene Islands. It has also spread into the Mediterranean Sea, where it now occurs from the eastern basin west to France and the Adriatic. Depths range from 2 to 40 m.
It is a day-active herbivore that grazes algae, including larger brown seaweeds, off the reef and hides in crevices at night. It is often seen in small schools, though solitary fish also occur. When threatened, it stops suddenly and erects its dorsal, anal, and pelvic fins to show off a ring of venomous spines.
This species is a Lessepsian migrant: it entered the Mediterranean through the Suez Canal, was first recorded off Israel in 1955, and has since spread as far west as France.
Describe what you saw and we name it, then keep every species you find in your Oceandex.