A journal Science-published study has unveiled about the discovery of first warm-blooded fish. The moonfish, also known as the opah, is quite a fast moving fish having great vision. The fish has quick reactions and high stamina.

The researchers have explained some of the great qualities of this warm-blooded fish. The researchers affirmed that the fish being warm-blooded acts as an active predator in the water. It is quite different from other fish that act sluggish in cold water.

Lead researcher Nicholas Wegner assessed the samples of the gill tissue of the fish. After observing them, Wegner noted that the opah’s tissue has blood vessels, which help the warm blood to be carried into the gills of the fish.

The blood vessels will then carry cold blood back to the body’s core after absorbing the oxygen from water, the phenomenon known as a counter-current heat exchange.

The researchers said the opah lives around 1,000 feet below the ocean’s surface where it is quite dark and cold. The opah flaps its fins to generate body heat and this flapping action also increases the fish’s metabolism.

The opah’s body temperature is around 41 degrees Fahrenheit and is more than its surrounding water. Wegner said the opah’s gills are quite different from other fish. Also, it is the first time that the researchers have observed counter-current heat exchange in the gills.

“There has never been anything like this seen in a fish's gills before. This is a cool innovation by these animals that gives them a competitive edge. The concept of counter-current heat exchange was invented in fish long before we thought of it”, affirmed Wegner.

It is the first time that a fish has been studied and showed to be a warm-blooded by nature. Therefore, now researchers are planning to take their research to next level to save the fish from being seafood.