Latin name

Decapterus russelli

Other name

Northern mackerel scad, round scad, Russell's mackerel scad, slender scad, or three lined grunter.

Identification

The body of the Indian scad is elongated, moderately slender, slightly compressed at the sides and covered with fine cycloid scales. The scales on the head do not extend forward beyond the centre of the eye. Eyes of moderate size, almost completely closed by the fatty eyelid, leaving only a small vertical slit in the centre of the eye. The tip of the upper jaw is straight when viewed from above and slightly concave when viewed from below. The teeth on both jaws are small, arranged in stripes on the front and in a single row on the sides. There are 10-14 gill stamens on the upper part of the first gill arch and 30-39 gill stamens on the lower part. The lateral line forms a low, elongated arch anteriorly and then (at the level of the 11-13 soft rays of the second dorsal fin) goes straight up to the caudal peduncle. The curved part has 42-62 scales and 0-4 bony flaps; the straight part has 0-4 scales and 30-40 bony flaps. Vertebrae: 10 dorsal and 14 caudal vertebrae.

Features of fish fins

Edge of secondary pectoral girdle (cleithrum) with two small tubercles. Two dorsal fins. The first dorsal fin has 8 hard rays, and the second dorsal fin has 1 hard ray and 28-33 (including an additional fin) soft rays. The anal fin has 1 barbed ray and 25-29 soft rays, with 2 barbs in front of the fin. The last soft ray of the dorsal and anal fins is separated from the other rays and is an additional fin. The pectoral fins are short (shorter than the length of the head), sickle-shaped. The caudal fin is deeply scored. 

Fish colouring

The upper part of the body is bluish-green, the sides and belly are silvery. There is a small black spot on the upper edge of the gill cover. The second dorsal fin is dark with a hyaline underside. The caudal fin and other fins are hyaline, except for darker pelvic fins in adult males.

Distribution

Widespread in the Indo-Pacific from the east coast of Africa to Indonesia, including all oceanic islands, and from Japan to Australia. Enters the Mediterranean via the Suez Canal.

Habitat

Marine benthopelagic fish. They live in coastal waters at depths of 40 to 275 metres. 

Size

The maximum length of these fish is 45 cm, usually up to 30 cm. Body weight - up to 110 g. According to other data, it can reach a mass of 0.7 kg. Maximum reported age: 12 years. 

Behavior

Indian scad form large aggregations, sometimes in small groups close to the shore in sheltered bays and coves. They remain near the bottom during the day, but disperse at night and rise closer to the surface. Most common in coastal waters and open coasts of the Indian Ocean. 

Food and feeding habits

Feeds on planktonic invertebrates. Adults feed in the middle and near bottom of the sea.

Reproduction

They reach sexual maturity during their first year of life when they are about 12 cm long.

Fishing

This species is a valuable commercial fish throughout its range. It is fished with purse seines and trawls. Thailand and Malaysia have the largest catches. 

Relationship with a person

This fish is sold in dried, salted and frozen form, and is also used for canning.