A tunny is another name for a tuna fish, especially the large Atlantic bluefin tuna that can weigh over 1,000 pounds. The word “tunny” is older and more common in British English, while Americans usually just say “tuna.”

For thousands of years, Mediterranean fishermen caught tunny using elaborate systems of nets. Ancient Romans prized tunny so highly they paid enormous sums for the best catches. Today, bluefin tunny remains one of the most valuable fish in the world. In 2019, a single bluefin tunny sold at a Tokyo fish market for over three million dollars because its meat is prized for sushi.

These powerful fish migrate across entire oceans, swimming thousands of miles between feeding and spawning grounds. Unlike most fish, tunny can keep their body temperature warmer than the surrounding water, which helps them swim faster and hunt more effectively in cold ocean depths.

When you see “tuna” on a menu or in a can at the grocery store, you're looking at tunny, though usually a smaller species than the massive Atlantic bluefin.