Siganus punctatus

Lore & Background

Siganus punctatus was first formally described in 1801 as Amphacanthus punctatus by Johann Gottlob Theaenus Schneider and Johann Reinhold Forster, with the type locality given as Nomuka Island in the Ha'apai Group of Tonga. The specific name punctatus means 'spotted', a reference to the golden spots on the head, body and tail. The species has a laterally compressed, deep body with a depth that fits into its standard length between 1.9 and 2.3 times. The head has a straight dorsal profile running from the forehead to the snout at a 45° angle, while the ventral profile is slightly indented under the chin. In fish under 13 cm standard length, the front nostril has a flap extending halfway to the rear nostril; this flap reduces to a low rim with a relict posterior peak once the fish reaches 15 cm standard length. A recumbent spine is embedded in the nape in front of the dorsal fin. Like all rabbitfishes, the dorsal fin has 13 spines and 10 soft rays, and the anal fin has 7 spines and 9 soft rays; the fin spines are robust and hold venom glands. The caudal fin is emarginate in individuals under 13 cm standard length, becoming deeply forked with broadly rounded lobe tips as the fish grows. The overall color is greyish with a dense pattern of brown spots with darker margins over the head, body and fins. There is sometimes a pale saddle on the caudal peduncle and a large ocellus to the rear of the upper margin of the gill cover. Juveniles have fewer, larger spots. A very narrow yellow margin on the caudal fin is frequently present.

Reader's Guide

Siganus punctatus has a wide Indo-West Pacific distribution, from the Cocos (Keeling) Islands in the eastern Indian Ocean east to Samoa, north to the Ryukyu and Ogasawara Islands of Japan, and south to Australia. In Australia, its range runs from Rottnest Island in Western Australia north and east along the northern tropical coast, then south on the east coast to North West Solitary Island in New South Wales; it is also found at Rowley Shoals, Scott Reef, Ashmore Reef, and in the Coral Sea at Coringa-Herald Cays and Lihou Reef. Adults occur down to 40 m depth in clear lagoons and on seaward reefs, while juveniles school in estuaries. Adults live in pairs on reefs; juveniles aggregate in schools of up to 50 fish, with school size declining as fish mature. Pairing begins once fish reach around 15 cm standard length, though fish as large as 22 cm may still be in schools. They feed on benthic algae. The species produces venom in the spines of its fins; a study of a congener found rabbitfish venom similar to stonefish venom. It is caught by spearfishing or in fish traps, sold fresh, and occasionally appears in the aquarium trade.

Did You Know?

• Juveniles school in estuaries, while adults live in pairs on reefs.
• A study of a congener found that rabbitfish venom is similar to stonefish venom.