Herring scad (Alepes vari)
Image source: Jakkarin Burananit | inaturalist.org
General data
- Main name: Herring scad
- Local names: Trevally scad, Duskyfin crevalle
- Climates: Tropical, Subtropical
- Habitat: Saltwater
- Native: Africa, Asia, Australia & Oceania
- Distribution: Pacific Ocean, Indian ocean
Classification
- Genus: Alepes - Alepes
- Family: Carangidae - Jacks
- Order: Carangiformes - Jacks
- Class: Actinopteri - Ray-finned fishes
- Superclass: Osteichthyes - Bony fishes
The herring scad (Alepes vari) (also known as the duskyfin crevalle and trevally scad), is a common species of tropical marine fish in the jack family Carangidae. The species inhabits the surface waters of coastal regions throughout the Indo-West Pacific region, feeding on a variety of crustaceans and small fishes.
It is the largest fish of the scad genus Alepes, growing to a recorded length of 56 cm.
The herring scad is identified among the genus Alepes by its more numerous and smaller scutes and the number of gill rakers on the first arch. It is of minor importance to fisheries throughout its range.
The herring scad has a body profile very similar to other members of the genus Alepes, having a strongly compressed, ovate body. The ventral and dorsal profiles of the fish are almost evenly convex, joined anteriorally by a pointed snout.There are two separate dorsal fins, the first containing 8 spines while the second has a single spine followed by 24 to 27 soft rays. The anal fin consists of two anteriorally detached small spines followed by a single spine connected to 20 to 23 soft rays.
The lateral line is strongly arched anteriorally with the junction of the curved and straight sections located the origin of second dorsal to the third soft ray. The curved section contains 42 to 50 scales and 0 to 2 scutes, while the straight section has 0 to 7 scales and 48 to 69 scutes.
There is a well-developed adipose eyelid on the posterior half of the eye. The jaws hold a single row of numerous comb like teeth. There are 32 to 38 gill rakers and a total of 24 vertebrae. The herring scad is by far the largest species in Alepes, growing to 56 cm in total length, although is more commonly encountered at below 30 cm.
The species is an ash blue above, fading to a silvery white below, with a diffuse dusky blotch on margin of operculum. The fins are dusky with the exception of the spinous dorsal fin which is pale to dark dusky. The amount of dark pigment in the fins is sexually dimorphic, with males developing darker spinous dorsal fin, lobes of soft dorsal and anal fins, and pelvic fins than females.