How to Identify Black Jack

To identify Black Jack (Caranx lugubris), look at these key features.

Physical Characteristics

Body shape

compressed

Coloration

Adults are typically uniformly dark grey to black dorsally, fading slightly to a dark silvery-grey ventrally. Fins are also dark, often black. Juveniles may exhibit faint vertical banding or a lighter overall coloration.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Deeply compressed, ovate body profile., Strongly curved dorsal profile and a less curved ventral profile., Large, prominent eyes., Strongly keeled scutes along the lateral line posteriorly., Absence of a dark spot on the operculum (gill cover), which distinguishes it from some other Caranx species.

Dorsal fin

Two dorsal fins; the first with 8 spines, the second with 1 spine and 20-22 soft rays. The anterior rays of the second dorsal fin are elongated, forming a distinct lobe.

Tail fin

Deeply forked caudal fin with long, pointed lobes.

Pectoral fin

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

Distinctive fins

Anal fin with 2 detached spines followed by 1 spine and 16-18 soft rays. The anterior rays of the anal fin are also elongated, mirroring the second dorsal fin lobe. The lateral line is strongly arched anteriorly, becoming straight posteriorly, with 26-32 strong scutes on the straight portion.

Identification Tips

1. 1

   Coloration

   Look for the uniformly dark grey to black body and fins, especially in adults. This is a key distinguishing feature.

2. 2

   Body Shape

   Note the deep, compressed body and the strongly curved dorsal profile.

3. 3

   Pectoral Fins

   Observe the long, sickle-shaped pectoral fins, which are typically longer than the head.

4. 4

   Scutes

   Feel or observe the prominent, strong scutes (large, bony scales) along the straight posterior section of the lateral line.

5. 5

   Opercular Spot

   Confirm the absence of a dark spot on the operculum, which helps differentiate it from other Caranx species like the Crevalle Jack (Caranx hippos).

Explore Black Jack