Longfin Waspfish

Apistus carinatus has a moderately elongated and compressed body. The lateral surface of the head is armed with a dense covering of bony ridges or keels. The rearmost pectoral fin ray is separate from the rest of the fin. There are between 14 and 16 spines and between 8 and 10 soft rays in the dorsal fin, with 3 or 4 spines and 6 to 8 soft rays in the anal fin. The overall colour is bluish to pinkish-grey, with a large black ocellus on the rear of the spiny part of the dorsal fin. The long pectoral fins are yellow, and there are sensory barbels on the chin. The ocellated waspfish attains a maximum total length of 20 cm (7.9 in) but 10 cm (3.9 in) is more typical.

Apistus carinatus has a wide distribution in the Indian and Pacific oceans. It occurs from the Red Sea south along the eastern coast of Africa to South Africa, east along the coasts of the Arabian Sea and into the Andaman Sea into the Pacific Ocean as far as the Philippines, north to the Bonin Islands and waters off Kyushu of Japan, and south to Australia. In Australian waters, this species occurs from Shark Bay in Western Australia around the northern coast and south as far as off Newcastle in New South Wales on the east coast. This species is a demersal fish which can be found at depths between 14 and 16 m (46 and 52 ft), although a more typical range is 15 to 50 m (49 to 164 ft), on sandy or silty substrates.

The genus name, Apistus, means "untrustworthy" or "perfidious", a name Cuvier explained as being due to the long and mobile spines around the eyes, which he described as "very offensive weapons that these fish use when you least expect it". The specific name, carinatus, means "keeled", presumed to be an allusion to the bony ridges on the head.