Side by Side

Blackfin Tuna Thunnus atlanticus

Typical: 20–28 in, 5–20 lb

Quickest tell: Dark finlets lacking bright yellow, on a deep football body with no back stripes, separate blackfin from the back-striped, fingerprint-spotted bonito/false albacore.

• Dark blue-black back, silver sides; deep football body with a chest corselet
• Finlets dusky/black, edged white-gray (NOT bright yellow as in other tunas)
• Short pectoral fins, not reaching past the second dorsal origin
• Smallest tuna; no oblique back stripes or fingerprint belly spots
• Faint yellow on the central finlets at most

Full Blackfin Tuna guide — season, gear and rules →

False Albacore Euthynnus alletteratus

Typical: 20–28 in, 5–12 lb

Key field mark: Worm-like scribbles confined to the back plus a few dark belly spots and a smooth UNMARKED lower body separate the albie from bonito, which carries straight slanted dark stripes onto its sides and has visible teeth.

• wavy, worm-like dark green-blue scribbles on the upper back only
• 3-7 dark round spots below and behind the pectoral fin
• lower sides and belly silvery and unmarked (no stripes)
• rigid tuna body with finlets before the tail; lacks scaly corselet markings of bonito
• small, inconspicuous teeth; deeply forked tail

Full False Albacore guide — season, gear and rules →

When Each Is Running July — current month highlighted

Where Blackfin Tuna and False Albacore Overlap

Both run in Southeast Atlantic — that is where telling them apart actually matters.

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