How to Identify Indo-Pacific Sailfish

To identify Indo-Pacific Sailfish (Istiophorus platypterus), look at these key features.

Physical Characteristics

Body shape

torpedo

Coloration

Dark blue to black dorsally, fading to silvery white on the flanks and belly. The dorsal fin is dark blue to black, often with scattered black spots. The flanks may have faint vertical bars or rows of spots, particularly when excited or feeding.

Scale type

none

Mouth position

terminal

Distinctive features

Extremely tall, sail-like dorsal fin that can be folded down into a groove along the back., Long, pointed bill (rostrum) that is round in cross-section., Slender, elongated body., Large, deeply forked caudal fin (tail).

Dorsal fin

The first dorsal fin is exceptionally tall and sail-like, comprising 42-49 rays. It extends nearly the entire length of the back. The second dorsal fin is small, located far back on the body, with 6-7 rays.

Tail fin

Large, deeply forked, and crescent-shaped, designed for high-speed propulsion.

Pectoral fin

Relatively long and narrow, with 18-20 rays.

Distinctive fins

Two anal fins; the first with 12-15 rays, the second with 6-7 rays. Pelvic fins are long and slender, almost reaching the anus, with 1 ray and 2-3 segments.

Identification Tips

1. 1

   Dorsal Fin

   The most prominent feature is the large, sail-like dorsal fin. When extended, it is much taller than the body depth. Note the dark blue/black coloration, often with spots.

2. 2

   Bill

   Possesses a long, pointed bill that is round in cross-section, distinguishing it from marlins which have a more flattened bill.

3. 3

   Body Coloration

   Dark blue to black on the back, silvery white on the belly. Look for faint vertical bars or rows of spots on the flanks, especially when the fish is active.

4. 4

   Pelvic Fins

   Long and slender, almost reaching the anus, which is a characteristic feature among billfishes.

Explore Indo-Pacific Sailfish