A new scientific article published in the journal Science reveals the only warm-blooded fish to be the Opah, also known as the Moonfish.

In a paper published this last week, Nicholas Wegner of the National Oceanic and Atmospheric Association shows that Opah are the only truly warm-blooded fish.

An excerpt from the paper states: “[They] describe a whole-body form of endothermy in a fish, the opah (Lampris guttatus), that produces heat through the constant “flapping” of wing-like pectoral fins and minimizes heat loss through a series of counter-current heat exchangers within its gills. Unlike other fish, opah distribute warmed blood throughout the body, including to the heart, enhancing physiological performance and buffering internal organ function while foraging in the cold, nutrient-rich waters below the ocean thermocline.”

Read the full paper published in the journal Science here.