Scientists find world's first fully warm-blooded fish: the ‘opah’

The warm fish: The opah is the first fish confirmed by science to be 100% warm-blooded.

Move over, mammals and birds, and make room for a fish called the opah (Lampris guttatus), confirmed by scientists in the journal Science as the world's first – and so far, the only – fully warm-blooded fish.

While tuna and certain sharks can warm specific regions of their body such as swimming muscles, brain and eyes in order to forage in chilly depths, they still need to return to the surface to protect vital organs such as the heart from the effects of the cold.