The Thornfish is a small fish ranging in length from 15-25 cm long. It has a cylindrical scaleless body with a wide flattened head, there are upward facing eyes and a wide mouth. There is a strong spine directed upward and backward on each gill cover behind the eyes. It has double dorsal fins, the first one is short and spiny. The heavy rays of the pelvic, pectoral and anal fins are used as props when the fish rests on the sea bottom. body and fin colour is variable and can be mottled with red, green, orange, pink and white on a background of olive brown to silvery red.

Often found in rock pools on exposed outer Southern Coasts although extremely difficult to see because they are so well camouflaged.

They feed on crustaceans and worms and can be quite aggressive predators.

NZ Marine Fishes: Paul Collins Guide to the Sea fishes of NZ: Ayling & Cox Paulin, C., Roberts, C., 1992, Rockpool Fishes of New Zealand. Museum of New Zealand, Te PapaTongarewa.