How to Identify Bigeye Trevally

To identify Bigeye Trevally (Caranx sexfasciatus), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Adults are typically silvery-grey to bluish-green dorsally, fading to silvery-white ventrally. Juveniles often exhibit 5-7 dark vertical bands on their flanks, which fade with age. The caudal fin is often yellowish to dusky. A distinct black spot is usually present on the upper operculum.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Large eyes, proportionally larger in juveniles, giving the species its common name., Strongly compressed, deep body., Prominent scutes (bony plates) along the lateral line, particularly on the posterior section., A small, detached finlet often present behind the second dorsal and anal fins in some individuals, though not a consistent diagnostic feature., A black spot on the operculum.

Dorsal fin

Two dorsal fins; the first with 8 spines, the second with 1 spine and 19-22 soft rays. The anterior rays of the second dorsal fin are elongated.

Tail fin

Deeply forked caudal fin, with long, pointed lobes.

Pectoral fin

Long, falcate (sickle-shaped) pectoral fins, longer than the head.

Distinctive fins

Anal fin with 2 detached spines followed by 1 spine and 15-17 soft rays. The anterior rays of the anal fin are also elongated, mirroring the second dorsal fin.

Identification Tips

1. 1

   Eyes

   Look for the proportionally large eyes, especially noticeable in smaller individuals, which are a key diagnostic feature.

2. 2

   Body Shape

   Observe the deep, compressed body profile, typical of many Caranx species.

3. 3

   Coloration and Bands

   Note the silvery body. Juveniles will have distinct dark vertical bands (usually 5-7), which fade or disappear in adults. The opercular spot is also a good indicator.

4. 4

   Scutes

   Feel or observe the prominent, bony scutes along the posterior part of the lateral line, a characteristic of jacks.

5. 5

   Fin Shape

   Identify the long, falcate pectoral fins and the deeply forked caudal fin.

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