Actinopterygii (ray-finned fishes) > Perciformes
(Perch-likes) > Siganidae
Etymology: Siganus: Latin, siganus = a fish, rabbit fish; by the similarity of the nose (Ref. 45335).
Environment / Climate / Range
Marine; reef-associated; depth range 0 - 40 m (Ref. 9813), usually 1 - 30 m (Ref. 27115). Tropical; 25°C - 29°C (Ref. 27115); 30°N - 30°S
Length at first maturity / Size / Weight / Age
Maturity: Lm ?, range 20 - ? cm
Max length : 40.0 cm TL male/unsexed; (Ref. 9813); common length : 25.0 cm TL male/unsexed; (Ref. 9813)
soft rays: 9;
Vertebrae: 13. Body blue above, silvery below; variations in markings (spots, curved lines) occur. Silvery-yellow iris. When frightened or asleep, entire fish becomes mottled with very light and dark browns, with dark ones predominating in 7 diagonal zones across the sides; fins become mottled. Spines slender, pungent, venomous. Preopercle angle 85°-95°. Fine scales on cheek. Midline of thorax without scales. Superficially resembles S. canaliculatus and S. fuscescens, particularly when young, but differs by having a much more deeply forked tail (Ref. 1602).
Indo-Pacific: Red Sea and East Africa to Pitcairn. Often the only siganid present on remote islands like Pitcairn, Rapa and Line.
Inhabits coastal and inner reef slopes and lagoons. Usually occurs in large schools that swim fast and well above the substrate, occasionally all diving down to the bottom to feed (Ref. 48637). Juveniles and adults occur in small schools (2-100) around coral reefs, typically in surge zone at reef edge. Juveniles live near the surface in dense aggregations up to several km offshore, migrating to reef flats just prior to metamorphosis. Feeds on algae (Ref. 30573). Juveniles and adults not frequently found in markets; but prejuveniles form a brief but important fishery when migrating on to the reef flat, e.g. combined catch (with Siganus spinus of 16 tonnes in one season in Guam. Prejuveniles eaten fresh, pickled in brine or made into fish paste (Ref. 9813). Consumed as food although it is known to be occasionally poisonous (Ref. 4537). Used in Chinese medicine (Ref. 12166).
Woodland, D.J., 1990. Revision of the fish family Siganidae with descriptions of two new species and comments on distribution and biology. Indo-Pac. Fish. (19):136 p.
IUCN Red List Status (Ref. 90363)
Fisheries: commercial; aquarium: commercial
Estimates of some properties based on empirical models
Phylogenetic diversity index (Ref. 82805
= 0.5000 [Uniqueness, from 0.5 = low to 2.0 = high].
Bayesian length-weight: a=0.01620 (0.01061 - 0.02473), b=3.03 (2.90 - 3.16), based on LWR estimates for species & Genus-BS (Ref. 93245
Trophic Level (Ref. 69278
): 2.0 ±0.0 se; Based on diet studies.
Resilience (Ref. 69278
): High, minimum population doubling time less than 15 months (K=0.75; tm=1).
Vulnerability (Ref. 59153
): Low vulnerability (22 of 100) .