Side by Side

Sailfish Istiophorus albicans

Typical: 6–7 ft, 30–50 lb

Quickest tell: The enormous sail-shaped dorsal fin, taller than the body's depth, instantly separates sailfish from the lower-finned marlins (keel count is shared by both, so use the fin).

• Huge sail-like first dorsal fin, far taller than the body is deep
• Long spear-like upper bill (rounded in cross-section)
• Cobalt blue back, silver sides with rows of pale blue spots/bars
• Slender body; very long, thin pelvic fins
• Two keels on each side of the tail base (billfish family)

Full Sailfish guide — season, gear and rules →

White Marlin Kajikia albida

Typical: 65–80 in, 40–70 lb

Key field mark: The unmistakable ROUNDED (paddle-like) tips of the first dorsal, pectoral, and anal fins, plus a dorsal nearly as tall as the body is deep, separate white marlin from the sharply pointed-finned, lower-dorsaled blue marlin.

• rounded (paddle-like) tips on the first dorsal, pectoral, and anal fins
• lighter green-blue back, often with dark spots on the dorsal fin
• first dorsal nearly as tall as the body is deep
• more slender, lighter body than a blue marlin
• spots and lighter coloration overall

Full White Marlin guide — season, gear and rules →

When Each Is Running September — current month highlighted

Where Sailfish and White Marlin Overlap

Both run in Puerto Rico & the U.S. Virgin Islands — that is where telling them apart actually matters.

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