Spotted rabbitfish

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 fish has a laterally compressed, deep body, with a straight dorsal profile running from the forehead to the snout at a 45° angle. In fish smaller than 13 cm standard length, the front nostril has a flap extending halfway to the rear nostril; this flap is reduced 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. 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 colour 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. There is frequently a very narrow yellow margin to the caudal fin.

Reader's Guide

The spotted rabbitfish is a species of moderate significance in its Indo-West Pacific range. It is caught by spearfishing or in fish traps and sold as fresh fish, and is occasionally found in the aquarium trade. Adults live in pairs on reefs, while juveniles aggregate in schools of up to 50 fish; the size of the schools declines as the fish mature, and they begin to pair off once they have attained a standard length of around 15 cm, 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 that rabbitfish venom was similar to the venom of stonefishes. Its distribution extends 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. It occurs down to 40 m in depth in clear lagoons and on seaward reefs as adults, while juveniles school in estuaries.

Did You Know?

• The fin spines are robust and hold venom glands; rabbitfish venom is similar to stonefish venom.
• Juveniles school in estuaries, while adults live in pairs on reefs down to 40 m depth.
• The caudal fin changes from emarginate in small fish to deeply forked with rounded lobe tips in larger individuals.