How to Identify Swordfish

To identify Swordfish (Xiphias gladius), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Dark brown to blackish-blue on the dorsal side, fading to lighter brown or silvery-white on the ventral side. Fins are typically dark brown or black.

Scale type

none

Mouth position

terminal

Distinctive features

Long, flattened, sword-like bill (rostrum), nearly round in cross-section, comprising about one-third of its total body length., Absence of scales in adults (juveniles have scales)., Absence of pelvic fins in adults., A single, high, crescent-shaped caudal fin (tail fin)., A prominent keel on each side of the caudal peduncle.

Dorsal fin

Two dorsal fins; the first is tall and sickle-shaped, located far forward on the back. The second is much smaller and located far back, near the caudal peduncle. In adults, the two dorsal fins are widely separated.

Tail fin

Large, rigid, and deeply forked (lunate or crescent-shaped), highly efficient for propulsion at high speeds.

Pectoral fin

Long and narrow, set low on the body, used for stability and maneuvering.

Distinctive fins

Absence of pelvic fins in adults. The anal fin is also divided into two, similar to the dorsal fins, with a large anterior fin and a small posterior fin.

Identification Tips

1. 1

   Bill Shape

   The most distinguishing feature is the long, flattened, sword-like bill, which is nearly round in cross-section. This differentiates it from marlins and sailfish, whose bills are rounder and more pointed.

2. 2

   Dorsal Fin

   Adult swordfish have a single, tall, sickle-shaped first dorsal fin and a very small, separate second dorsal fin. Unlike marlins, the first dorsal fin does not extend along the back.

3. 3

   Pelvic Fins

   Adult swordfish completely lack pelvic fins, a key distinguishing characteristic from all other billfish species.

4. 4

   Scales

   Adult swordfish are scaleless, possessing only rough dermal denticles, whereas other billfish retain scales.

5. 5

   Caudal Keels

   Possess a single, prominent lateral keel on each side of the caudal peduncle, unlike marlins which have two.

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