Coachwhip trevally
(Carangoides oblongus)

The coachwhip trevally (Carangoides oblongus), also known as the oblong trevally or oblique-banded trevally, is a species of inshore marine fish classified in the jack family Carangidae.

The coachwhip trevally is distributed through the Indo-west Pacific region, ranging from South Africa in the west to Fiji and Japan in the east.

It is a moderately large fish, growing to a known maximum length of 46 cm and can be distinguished from similar species by an array of detailed morphological features including dentition, fin ray counts and scale patterns.

It is quite similar in appearance to a number of co-occurring trevallies, especially C. armatus and Atropus atropos, with the simplest identifying feature being the distinct break in the contour (bump) of the interorbital region, which becomes more pronounced with increasing size. The body is compressed and deep, with the head profile very steep in adults, leading to a more convex dorsal profile in comparison to the ventral profile.

The dorsal fin is in two sections, the first consisting of eight spines while the second has one spine and between 20 and 22 soft rays. The anal fin has two anteriorly detached spines followed by 1 spine and 16 to 18 soft rays, while the pelvic fin has one spine and 18 soft rays. The lobes of the second dorsal and anal fins are elongated and filamentous, being longer than the head. In males, a number of the central soft rays are also produced into filaments of varying lengths.

The lateral line has a moderate anterior arch, which contains 63 to 70 scales, while the straight section has eight to 14 scales and 21 to 27 scutes. The curved and straight sections intersect below the 10th to 12th soft rays of the second dorsal fin.

The breast is devoid of scales, with the scaleless area extending to the origin of the pelvic fins and up to the base of the pectoral fins. Both jaws have bands of villiform teeth, which are widest anteriorly. It has a total of 20 to 27 gill rakers and 24 vertebrae.

The body of the bumpnose trevally is a silvery green-blue above, becoming more silvery-white below, with a dark blotch present on the operculum. The spinous dorsal fin and the soft dorsal fin rays are black, while the anal fin is brownish, with the filaments and lobe often blackish. The caudal fin has black trailing and leading edges, and the pelvic fin is dusky to black. Juveniles often have five to seven vertical crossbars on their sides.

The coachwhip trevally inhabits coastal waters throughout its range, known to prefer estuarine waters in a number of localities. Nothing is known of its diet or reproductive biology, and is of little importance to fisheries, occasionally taken as bycatch in trawl and hook and line fisheries.