
The Blackblotched Porcupinefish has erectile spines on the head and body. Like all members of the family, it can inflate its body with water, and turn itself into a very spiny ball.
The body is brown to grey above shading to white below. There are white-margined dark blotches on the back and sides, and the fins are normally unspotted. It is similar to the Freckled Porcupinefish, but the latter has much longer spines, particularly on the head, and the blotch on the top of the head is continuous between the eyes.
It grows to about 45 cm in length.
The species is occurs in tropical waters of the Indo-west and Central Pacific, from South Africa, north to Japan, south to Australia and east to the Marshall and Society Islands.
It is found on coral and rocky reefs and inshore waters.
In Australia it is known from the central coast of Western Australia, around the tropical north and south on the east coast to southern New South Wales.
It has also been called the Blotched Porcupinefish and Brown-backed Porcupinefish.