Based on scientific studies, fishes are concentrated cold-blooded, but the discovery of Opah fish, made that fact at stake. Scientist found out that the Opah fish is a warm-blooded animal like us humans and other mammals.
Nicholas Wegner, study leader at biologist in Southwest Fisheries Science Center of National Oceanic and Atmospheric Administration (NOAA) Fisheries in La Jolla, California said that the majority of fish are exotherms, which means they need heat from their environment to survive.
As an endotherm, the Opah or Lampris guttatus is maintaining its body temperature by heating up the surrounding water they plunged in, with this ability they can even reached diving the depths of 1,300 feet (396 meters).
Commonly called as moonfish, with small red fins and giant oval-shaped body reaching six feet (1.8 meters) long. The fins warm up the body of this rare fish, in addition to the heat of the water from sunlight.
It appears that heat produces in the body of Opah is the energy generated from the movement of its fins while swimming.
The researchers first suspected that there was something different in Opah after reviewing a sample of gill tissue of fish. According to the new study, the blood vessels in tissue that carries cold oxygenated blood from the gills to the body is linked to the warmth, in turn bringing warm, deoxygenated blood from the body to the gills.