How to Identify Blue Runner

To identify Blue Runner (Carangoides crysos), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Dorsal side is typically dark blue to blue-green, fading to silvery-white on the flanks and belly. A small, distinct black spot is usually present on the upper operculum (gill cover) and at the base of the pectoral fin. Juveniles may have 5-7 dark vertical bars on their sides, which fade with age.

Scale type

cycloid

Mouth position

terminal

Distinctive features

Streamlined, fusiform body adapted for speed., Laterally compressed., Large eyes., Strongly forked caudal fin., Prominent scutes (bony plates) along the posterior part of the lateral line, numbering 50-60., A small, dark opercular spot., Adipose eyelid well developed, covering most of the eye except for a central slit.

Dorsal fin

Two dorsal fins. The first dorsal fin has 8 spines, followed by a second dorsal fin with 1 spine and 23-27 soft rays. The anterior rays of the second dorsal fin are elongated.

Tail fin

Deeply forked and powerful, characteristic of fast-swimming pelagic fish.

Pectoral fin

Long and falcate (sickle-shaped), extending beyond the origin of the second dorsal fin. Contains 19-21 rays.

Distinctive fins

Anal fin has 2 detached spines followed by 1 spine and 19-23 soft rays. Pelvic fins are relatively small.

Identification Tips

1. 1

   Body Shape and Coloration

   Look for the streamlined, torpedo-shaped body, dark blue-green dorsal fading to silvery-white. The small black spot on the operculum and pectoral fin base is a key identifier.

2. 2

   Lateral Line Scutes

   Feel or observe the prominent, hard scutes along the posterior part of the lateral line. There are typically 50-60 of these bony plates, which are a defining characteristic of many Carangidae.

3. 3

   Fin Structure

   Note the two distinct dorsal fins, with the anterior rays of the second dorsal being elongated. The deeply forked caudal fin is also indicative of its fast-swimming nature.

4. 4

   Adipose Eyelid

   The well-developed adipose eyelid, covering most of the eye, is a subtle but consistent feature.

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