Roundbelly Cowfish

Lactoria diaphana has a thick, rectangular body that is largely enclosed in a carapace which is made up of thickened, hexagonal plate -like scales which are jointed to each other. There are five horizontal ridges on the carapace, a poorly developed one along the back and a pair, upper and lower, on each flank. There is a large spine above each eye and a spine at the rear end of each of the lower flank ridges and there is a spine halfway along the ridge along the back. They have small mouths located at the front of the snout, with fleshy lips and a row of no more than 15 moderately sized conical teeth in each jaw. The gill slits are short and oblique and are to the front of the bases of the pectoral fins. The dorsa and anal fins are at the back of the carapace and the caudal peduncle is thin and flexible. The caudal fin is fan shaped. The dorsal fin has 9 soft rays, as does the anal fin. The dorsal profile of the snout is steep and concave while the vetral profile of the body is rounded. The overall colour i and concave while the ventrals pale greensih-grey patterned with a honeycomb reticulation and brown blotches. The roundbelly cowfish has a maximum total length of 34 cm (13 in).

Lactoria diaphana has a wide distribution in the Indo-Pacific where it extends from the eastern coast of Africa in the western Indian Ocean where it's found off Mozambique and South Africa through the Indian and Pacific Oceans as far as the eastern Pacific between Santa Barbara, California and Chile. It extends as far north as Japan and south to Tasmania. This species is the only member of the genus Lactoria with a range that extends into the southeastern Atlantic as it is found around the Cape of Good Hope and along the southwestern coast of Africa as far north as Swakopmund, Namibia. The roundbelly cowfish is found on coastal and outer reefs, at depths down to 50 m (160 ft). The juveniles are semi-transparent and are found in pelagic waters close to the surface

Lactoria diaphana is classified within the genus Lactoria, an name that means a "milkcow", a reference to the large spines above the eyes resembling the horns of a cow. The fishes in this genus are known as cowfishes, as are some related species. The specific name diaphana, means "transparent", as it appears that the holotype was a transparent juvenile.