The opah is turning biology on its head as it has been confirmed by scientists to be the first known warm-blooded fish. Specially designed blood vessels in its gills allow the fish to circulate warm blood throughout its body. There are only two known species of opah, one is known only as opah and the other as the southern opah.
Scientists have long suspected the opah was unusual. It is found in deep waters, where all fish, even predators, are slow moving due to the cold temperatures. But the opah has all the characteristics of a fast moving animal – a large heart, many muscles, and large eyes.