All fish are cold-blooded.
Just a week ago, that statement would have been true. But on Thursday, scientists announced they discovered the world’s first warm-blooded fish, the opah, forcing us to rethink some of the most basic biological concepts we learned back in elementary school.
Opah, also known as moonfish, are rotund — almost comically so — predatory fish that hunt for prey in cold, dark waters up to 1,000 feet below the ocean’s surface. Although they aren’t fished commerci