Bigeye Tuna Identification Guide

Key identification features

• Deep-bodied, robust tuna often exceeding 6 feet in large adults
• Unusually large eye diameter relative to head size, giving the species its name
• Dark metallic blue back transitioning to silvery-white belly with faint vertical lines
• Moderately long pectoral fins reaching to or just past the start of the second dorsal fin
• Short finlets behind the dorsal and anal fins, yellow with narrow dark edges
• Liver typically pale and unstriated internally, a trait used in dockside ID

Common look-alikes

• Yellowfin Tuna: has notably longer, sickle-shaped second dorsal and anal fins in adults, and smaller eyes
• Blackfin Tuna: much smaller overall size and shorter pectoral fins that fall well short of the second dorsal
• Albacore: has extremely long pectoral fins reaching past the anal fin origin, unlike Bigeye's shorter fins

Where you'll see one

Bigeye Tuna inhabit tropical and subtropical waters of the Atlantic, Pacific, and Indian Oceans, typically staying deeper in the water column than other tunas and often found near seamounts, current edges, and open offshore waters far from the coast.