Researchers from Japan have identified and clarified the biological name of the world’s heaviest bony fish ever caught.
The 2,300 kilogram whopper is a Mola alexandrini bump-head sunfish, and not, as originally thought, a member of the more commonly known Mola mola ocean sunfish species.
Bony fish have skeletons made of bone rather than cartilage, as is the case for sharks or rays. Ocean sunfishes count among the world’s largest bony fish, and have for centuries attracted interest from seafarers because of their impressive size and shape.
Specimens can measure up to three meters (total length), and many weighing more than two thousand kilograms have been caught. Instead of a caudal fin, sunfish have a broad rudder-like lobe called a clavus.
Ocean sunfishes can be classified into three species which Sawai’s team temporarily called Mola species A, Mola species B, and Mola species C, respectively. Of the three species, the scientific name of Mola species C was officially named Mola tecta in July 2017.
The Guinness World Records lists the world’s heaviest bony fish as Mola mola. However, Sawai’s team found a female Mola alexandrini specimen of 2,300 kilogram and 2.72 meter caught off the Japanese coast (Kamogawa, Chiba) in 1996 as the heaviest bony fish ever recorded. Through their investigations, Sawai’s team re-identified it as actually being a Mola alexandrini based on its characteristic head bump, chin bump and rounded clavus although this specimen was identified Mola mola until now.