Sailfish Identification Guide
Spot a sailfish by its towering sail-like dorsal fin and long, slender spear-like bill.
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Key identification features
- Enormous, sail-shaped first dorsal fin that is taller than the body is deep, usually held folded down while swimming and raised when excited
- Long, slender, pointed bill (rostrum) extending from the upper jaw
- Cobalt-blue to gray-blue back with rows of pale blue spots or vertical bars along the flanks
- Silvery-white belly and a sharply tapered, laterally compressed body
- Two small keels on either side of the tail base
- Slender build reaching up to 3 m and around 60 kg
Common look-alikes
- Blue marlin and white marlin: both have a much lower, shorter dorsal fin that never approaches sail height, plus a stockier, rounder body
- Swordfish: lacks pelvic fins entirely, has a flat, wide bill instead of a round spear, and has no sail-like dorsal fin
- Spearfish species: shorter bill relative to body and a dorsal fin that is tall only near the front rather than running the length of the back
Where you'll see one
Sailfish roam warm, open ocean waters worldwide near the surface, often traveling in loose groups and frequently seen leaping or "sailing" with the dorsal fin raised above the surface offshore.
Frequently asked questions
How do I tell a sailfish from a marlin?
The sailfish's dorsal fin is dramatically taller than its body depth, unmistakably higher than the comparatively low, short dorsal fin of any marlin species.
How do I tell a sailfish from a swordfish?
A sailfish has a round, slender bill, visible pelvic fins, and a tall sail fin, while a swordfish has a flat wide bill, no pelvic fins, and no sail.