Scientists Identify the World's First Warm-Blooded Fish

This opah was caught during an NOAA Fisheries survey off the California coast. (Credit: NOAA Fisheries/Southwest Fisheries Science Center) 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.