Description
Dorsal spines (total): 13; Dorsal soft rays (total): 10; Anal spines: 7; Anal soft rays: 9; Pectoral fin rays: 16-17; Scale rows between lateral line and bases of leading dorsal-fin spines: 18-27; Body deep and compressed, its depth: 1.8-2.2 times in SL; Snout: 1.8-2.2 in Head; Dorsal profile of head descending fairly steeply, slightly concave in front of eye; Anterior nostril with a low flange slightly expanded posteriorly; A forward-directed spine in front of dorsal fin, imbedded in nape; Fourth to eighth dorsal-fin spine longest, only a little longer (1.1-1.3 times) than last dorsalfin spine; Last anal-fin spine longest, slightly longer (1.1-1.2 times) than longest dorsal-fin spine; Caudal fin emarginate to moderately forked. Scales minute; Cheeks covered with prominent scales. Max. length: 43.0 cm TL, common length: 25.0 cm TL. Depth range: 0 - 25 m.

Color
Blue above to silver below; Horizontal golden bronze bands, some broken, running along single sides of trunk, breaking up into spots near bases of dorsal and anal fins and on caudal peduncle, and spots also on nape. Head golden with blue spots and lines convoluted into various shapes, the most constant being a diagonal line across cheek from below orbit to corner of mouth. Iris silvery, unspotted. A bright yellow spot about size of orbit on sides at base of last few rays of dorsal fin. Dorsal-fin spines golden on a dusky bronze membrane; Dorsal-fin rays silvery on a bluish membrane, with a row of golden spots at bases of rays; Anal-fin spines golden bronze on dusky blue membrane; Anal-fin rays bluish, membrane dusky with a golden spot at base and a bar above it in each cell of the membrane. Caudal fin bluish with rows of golden spots which appear as 3-4 cross bars on the folded fin; Outer spine and ray of pelvic fins silvery, remainder dusky blue; Pectoral fins hyaline.

Etymology
Siganus: Latin transformation of the Arabic word, sijān = a fish, rabbit fish. Referring to the similarity of the nose.
lineatus: from Latin, lineatus = line. Described as having 9-10 wavy bands or lines, tawny in color, running length of body.
Original description: Amphacanthus lineatus Valenciennes, 1835 - Type locality: Vanikoro, Island from the Santa Cruz group, Solomon Islands and New Guinea.

Distribution
Indo-West Pacific: Maldives and Sri Lanka east to Palau, Yap, New Ireland (Papua New Guinea), Solomon Islands and Vanuatu, north to Philippines, south to northern Australia and New Caledonia.

Biology
Juveniles found in mangrove areas and seagrass flats; Adults in protected waters such as lagoons and bays in the vicinity of rocky substrata or reefs. Forms schools that diminish with age, down to 10-25 fish by adult stage, although congregations may consist of several thousand fish during spawning period. Feeds by scraping encrusting algae from beach rock or pavement areas of coral reefs or by browsing on larger coarse algae. Smallest female to spawn was 23 cm, the largest 33 cm SL. Spawning apparently occurs not until the fish is 2 years old.

Similar species
Siganus guttatus (Bloch, 1787) - Reported from Indo-West Pacific: Lakshadweep (India), Myanmar, Andaman Islands and Indonesia east to West Papua (Indonesia), north to Ryukyu Islands (Japan), south to northern Australia.
Siganus insomnis (Woodland & Anderson, 2014) - Reported from Northern Indian Ocean: Maldives, Sri Lanka and southern India.

Last update: 24, March 2023