How to Identify Diamond Trevally

To identify Diamond Trevally (Trachinotus baillonii), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Silvery body, often with a darker dorsal surface fading to white ventrally. Juveniles and sub-adults typically display 3-7 prominent, round to oval black spots along the lateral line, which may fade or become less distinct in very large adults. Fins are typically dusky or yellowish.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Deeply compressed, oval to diamond-shaped body, especially in juveniles., Small, embedded scales., Prominent black spots (3-7) along the lateral line, particularly visible in younger individuals., Pointed snout and small, terminal mouth., Strongly forked caudal fin.

Dorsal fin

Two dorsal fins; the first with 6-7 short, stout spines (often embedded in adults), and the second with 1 spine and 23-27 soft rays. The anterior rays of the second dorsal fin are elongated, forming a sickle shape.

Tail fin

Deeply forked, with long, pointed lobes.

Pectoral fin

Long and falcate (sickle-shaped), extending beyond the origin of the anal fin.

Distinctive fins

Anal fin with 2 detached spines followed by 1 spine and 22-25 soft rays, similar in shape to the second dorsal fin. Pelvic fins are relatively small.

Identification Tips

1. 1

   Body Shape

   Look for the highly compressed, oval to diamond-shaped body, especially noticeable in younger fish.

2. 2

   Spots

   Count the distinct black spots (usually 3-7) along the lateral line. These are a key identifier, though they can fade in very large specimens.

3. 3

   Fin Shape

   Observe the long, falcate pectoral fins and the deeply forked caudal fin. The anterior rays of the second dorsal and anal fins are elongated.

4. 4

   Snout

   Note the pointed snout and small, terminal mouth.

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