Orange-spotted spinefoot

Lore & Background

The orange-spotted spinefoot was first formally described in 1787 as Chaetodon guttatus by the German physician and naturalist Marcus Elieser Bloch, with the type locality given as the East Indies. The specific name guttatus means 'spotted', a reference to the rusty spots on the flanks of this fish. Its body is laterally compressed, with a depth approximately half its standard length, and the dorsal profile of the head is quite steep with a slight indentation to the front of the eyes. The front nostril has a slightly raised edge larger than the rear, and there is a forward-pointing spine embedded in the nape in front of the dorsal fin. The dorsal fin has 13 spines and 10 soft rays, while the anal fin has 7 spines and 9 soft rays. The caudal fin is emarginate, becoming moderately forked in the largest individuals. The overall colour is dusky blue above and silvery below, with a single large yellow-orange spot below the soft-rayed part of the dorsal fin near the caudal fin, and a number of smaller reddish-brown spots on the flanks.

The species has a wide Indo-West Pacific range from the Andaman Islands and the western coast of Peninsular Malaysia and Sumatra to West Papua, north as far as the southern Ryukyu Islands. It is uncommon in Palau and has been recorded from Yap. It is found to depths of 35 m in shallow coastal waters, inhabiting reefs and mangroves, and can tolerate a wide variety of salinities. The fry first settle in beds of sea grass near river mouths, and adults enter and leave tidal river channels with the tide. Adults also occur on drop-offs of coastal fringing reefs. This is a schooling species, with adults forming schools of between 10 and 15 fishes. Their diet is mainly benthic algae. Unusually for a rabbitfish, the orange-spotted spinefoot may be active at night, and spawning normally takes place around midnight.

Reader's Guide

The orange-spotted spinefoot is notable for its venomous spines: grooves in the spines of the dorsal, anal and pelvic fins contain venom glands, and the wound caused by these spines may be relatively painful to humans, though usually not dangerous. The spines are used in self-defence. A study of the venom of a congener found that rabbitfish venom was similar to the venom of stonefishes. The species is fished using set nets and fish traps and is common in markets where it is sold as fresh fish. Rabbitfishes are considered good candidates for aquaculture, and there is mounting interest in the commercial culture of S. guttatus. It has mariculture potential because it is hardy in culture, there is an abundance of wild fry and spawners, and its herbivorous diet gives it the potential to be an inexpensive source of protein for mass consumption. It also appears in the aquarium trade. Its wide distribution, tolerance of varied salinities, and schooling behaviour contribute to its ecological and economic significance in the regions where it occurs.