Bloch's Gizzard Shad

Diagnosis: Body rather deep, its depth about 34-41% of standard length, belly with 17-20 + 9-13 scutes, total 28-32 scutes; anterior arm of pre-operculum with the third infra-orbital bone immediately above it, no fleshy gap between; mouth inferior, lower jaw strongly flared outward; last dorsal finray filamentous; pectoral axillary scale present; hind edge of scales distinctly toothed; a dark spot behind gill opening (Ref. 188). Resembles Nematalosa galatheae, which has spots along the flank and a smooth hind edge to scales; Nematalosa arabica, N. come and N. japonica all have a distinct fleshy triangular area above the anterior arm of the pre-operculum and none have toothed scale edges; no other clupeid in the distribution area of Nematalosa nasus has a filamentous dorsal finray (Ref. 188).Description: Body rather deep, its depth about 34-41% of standard length (Ref. 188). Lower jaw flared outward (Ref. 3259). Gill rakers very numerous, the number increasing with growth (Ref. 3259). Dorsal fin with 3-5 unbranched and 12-14 branched rays, anal fin with 2-3 unbranched and 19-22 branched rays, pectoral fin with 1 unbranched and 12-16 branched rays, pelvic fin with 1 unbranched and 7 branched rays (Ref. 3259). Scales on lateral line 46-49; hind edge of scales toothed in adults (Ref. 3259). With 17-20 pre-pelvic scutes and 9-13 post-pelvic scutes (Ref. 188, 3259).Colouration: Body and head dark bluish dorsally, silvery below; a dark spot behind gill opening (Ref. 188, 3259).

Anadromous. Fish that ascend rivers to spawn, as salmon and hilsa do. Sub-division of diadromous. Migrations should be cyclical and predictable and cover more than 100 km.

Dorsal spines (total): 0; Dorsal soft rays (total): 15 - 19; Analspines: 0; Analsoft rays: 21 - 25

Inhabits coral reefs (Ref. 58534). Adults are marine. Adults and juveniles frequently visit mangroves and brackish waters (Ref. 43081).

Known from estuaries and coastal areas, occasionally ascending into the upper reaches of the tidal zone (Ref. 12693). A filter-feeder. Marketed fresh, dried-salted or boiled. Made into fish balls. Very bony.

fisheries: minor commercial; price category: low; price reliability: very questionable: based on ex-vessel price for species in this family

分布於印度-西太平洋區，由波斯灣、安達曼海、中南半島、南中國海到韓國。臺灣西南部沿海較常見。

本種魚產量並不大，常混於底拖漁獲中，可生鮮、乾製或醃漬出售。中部地區喜以之煮湯食用，油炸亦甚美味。主要漁法為流刺網、圍網與拖網。

體呈長卵圓形，側扁，腹緣具鋸齒狀的稜鱗，17-18+14-15個。頭中大。吻短而鈍突。眼側位，脂性眼瞼發達。口下位，平直；無齒；上頜突出於下領，上頜骨末端向下彎曲，向後延伸至眼前緣下方。鰓蓋光滑；前鰓蓋骨下支上方無三角形之肌肉。體被橢圓形圓鱗，鱗片後緣之具鋸齒狀，縱列鱗45-50；背鰭前不具中線鱗；胸鰭和腹鰭基部具腋鱗。背鰭位於體中部前方，具軟條15-16，末端軟條延長如絲；臀鰭起點於背鰭基底後方，具軟條20-24；腹鰭軟條8；尾鰭深叉。體背部綠褐色，體側下方和腹部銀白色；鰓蓋後上方具一大黑斑，其後有數列黑色小點狀縱帶。背鰭、胸鰭、尾鰭淡黃色；餘鰭淡色。

為海洋性近沿海洄游小型魚類，亦常可發現於河口區產卵。有集群洄游之習性，並有強烈之趨光性產卵季在春夏之間，分批產卵，產卵後，魚群分散索餌。以矽藻、橈腳類及其它小型無脊椎動物為主要食物。

The Bloch's gizzard shad (Nematalosa nasus), also known as gizzard shad, hairback, long-finned gizzard shad, long-ray bony bream and thread-finned gizzard shad, are a widespread and common, small to medium-sized anadromous fish found in all marine, freshwater and brackish waters throughout Indo-West Pacific, towards eastward of Andaman Sea, South China Sea and the Philippines to Korean peninsula. Single specimen recorded from waters of South Africa. It was described by Marcus Elieser Bloch in 1795.

The sardines are known to swim at a maximum depth of 30 metres. The largest known standard length for the species is 22 cm. The fish can separate from its sister species by the presence of a dark spot behind gill opening. Belly consists with 17 to 20and 9 to 13 scutes. It has 15 to 19 dorsal soft rays and 17 to 26 anal dorsal soft rays. It is a filter feeder and feeds on planktons. Widely used as a food fish, it can make in to fish balls and can eat both as fresh and dried forms.