Yellowfin are a true prize among game fish and are the most strikingly colored of the tunas. Their coloration ranges from blue to black along the fish’s back, silver to silvery gold on the flanks and silvery white towards the belly. A band of bright gold or iridescent blue (sometimes both) runs along the upper flank, separating the dark back from the lighter belly area. As the name suggests, the tuna’s fins are bright yellow—the finlets in particular are canary yellow with black margins. The tail fin is distinctly notched in an "M" shape at the center of its fork.
Adult yellowfin are distinguished by a long pectoral fin that is one-third to one-fourth the body length. In large fish, the second dorsal and anal fins may be elongated and bright yellow.
The Pacific coasts of Mexico, Costa Rica and Panama, where light tackle fishing for large pelagic species has been honed to an art form, are perhaps the best places to chase yellowfin. Even so, these large, fast, pelagic fish are almost too much of a challenge for the fly rodder. Nevertheless, juveniles are caught each year by anglers chasing sailfish and smaller billfish. Tackle for tackling yellowfin should be the stoutest available. Anglers routinely use rod weights in the ‘teens with the biggest, toughest reels that money can buy in the hopes of boating a baby yellowfin.
Yellowfin are primarily offshore species that roam the world’s oceans and prefer warm currents, such as the Gulf Stream in the western Atlantic. Such currents often bring them close to shore during the warmer months of the summer, which gives small boat anglers a shot at these amazing game fish.
The yellowfin is found throughout the world’s oceans in deep, warm waters. It is migratory and has been known to come close to shore if the current is warm enough. The largest yellowfin are routinely found off the coast of Baja California, where every year fish in the three hundred pound class are boated.