The ocean sunfish or common mola (Mola mola) is one of the heaviest bony fishes in the world weighing between 545 and 4,409 pounds. The name Mola means "millstone" in Latin and refers to the circular shape of the fish.
Sometimes these fishes are mistaken for sharks as this excerpt explains: "Silvery in color and rough to the touch, these animals are found in tropical and temperate oceans around the globe. They’re often mistaken for sharks due to their enormous dorsal fins that peek out of the water.
Per reports, the heaviest bony fish ever caught weighs in at a staggering 5,070 lbs (2,300 kilograms): "The largest catch on record was actually an M. alexandrini caught in 1996 off Kamogawa, Japan. That fish was 8.9 feet (2.72 m) long, raising the question of whether some individuals of this species are even heavier."
An interesting fact about the sunfish is that their teeth are fused into a beak-like structure which makes it impossible for them to fully close their mouths. Their diet consists of small fishes, fish larvae, squid, and crustaceans.
The sunfish's love for soaking in the sun's rays while floating on the surface is what gave them the name "sunfish". Though their formidable size serves as a deterrent to most predators, it does not protect them from human beings as this excerpt explains: "Unfortunately, this tendency to drift along near the surface has caused these massive fish to get annihilated by passing boats on a regular basis. As such, the species’ 10-year lifespan is often cut short by a mere appreciation of soaking up some sun."
This threat has resulted in these gentle giants being declared a vulnerable species.