Tuna in Animal Crossing: New Horizons aren't like your average fish. They're one of the rarest catches in the game, only spawning during certain conditions and being a general pain for players looking to fill their Critterpedia. It has gone down in the history books with the likes of the Coelacanth, Barreleye and Oarfish.
Here's everything you need to know about catching a tuna in Animal Crossing: New Horizons.
Tuna in Animal Crossing: New Horizons: The Best Time to Catch Tuna
Tuna can be found by casting your line off the edge of your island's pier. Each island as at least one pier—a long stretch of boards that extends further into the sea than your shore. It is an optimal place for fishing as several of the rarest types of fish can be found here. Perhaps it has something to do with getting deep into the sea?
Tuna can only be caught from November through April in the Northern Hemisphere—opposite the Southern Hemisphere. They're much more likely to spawn when it rains so its best to plan for this weather accordingly. Fish bait can be used to bring them to the surface.
Once caught, an individual tuna can be sold to the Nooks for 7000 bells each. Personally, we consider this a better opportunity than All-Arachnophobia Island—all fishing and no fainting.