White-spotted spinefoot

Lore & Background

Siganus canaliculatus was first formally described in 1797 as Chaetodon canaliculatus by Scottish explorer Mungo Park, with the type locality given as Bengkulu Province on Sumatra. The specific name canaliculatus means 'grooved', a reference to the grooves in the fin spines; Park did not know that these spines contained venom glands for defence. This taxon is largely sympatric with the mottled spinefoot (Siganus fuscescens) and they are very similar in appearance. Molecular analyses in 2011 found three separate lineages within S. canaliculatus and S. fuscescens that interbred, suggesting S. canaliculatus may be a junior synonym of S. fuscescens, though FishBase and Catalog of Fishes do not take this position.

The colour and pattern of the white-spotted spinefoot is very variable, ranging from greenish grey to yellow brown, marked with 100–200 pearlescent blue to whitish spots on the nape and anterior body. Alarmed or injured fishes adopt a mottled pattern of light and dark brown and cream. The species has a moderately slender, laterally compressed body, with a pointed snout and a forward-pointing front spine on the dorsal fin. Juveniles form very large schools, which reduce in size as the fish mature; adults occur in groups of around 20 individuals. Spawning occurs from April to July, with a possible secondary period in November, and is synchronised with the lunar cycle. A mature female can spawn multiple times in a season, laying up to a million eggs.

Reader's Guide

The white-spotted spinefoot is an important quarry species for commercial fisheries. In the Persian Gulf it is considered a good quality food fish, though rather small, and is caught using bottom trawls, seine nets, intertidal net fences, and dome-shaped metal traps called gargoors. The fish are sold fresh in large numbers, and it is also taken as bycatch. Among the Teochews of Singapore and Malaysia, it is particularly fondly referred to as pek tor her (Chinese: 白肚鱼; lit. 'white rabbit fish'), typically steamed and eaten with rice or as part of Teochew porridge. It is especially popular during Chinese New Year, when the fish is heavy with milt and roe and its consumption is considered auspicious, earning it the name pai ni her (Chinese: 拜年鱼; lit. 'Chinese New Year fish'). The species has been used for mariculture in some areas due to its herbivorous habits, rapid growth, and economic value, though in some parts of its range the stock has been overfished. The article also notes that the white-spotted spinefoot was found to be a host of an intestinal acanthocephalan worm, Diplosentis amphacanthi.

Did You Know?

• The white-spotted spinefoot was first described in 1797 by Scottish explorer Mungo Park as Chaetodon canaliculatus.
• Molecular analyses in 2011 suggested Siganus canaliculatus may be a junior synonym of Siganus fuscescens, but this is not accepted by FishBase or Catalog of Fishes.
• A mature female can spawn up to a million eggs in a season, with spawning synchronised to the lunar cycle.
• The Teochews of Singapore and Malaysia call it pek tor her, meaning 'white rabbit fish', and eat it steamed during Chinese New Year.