World's heaviest bony fish discovered in Japan

Tokyo: The world's heaviest bony fish ever caught - weighing a whopping 2,300 kilogrammes - has been identified and correctly named by Japanese experts. The fish is a Mola alexandrini bump-head sunfish, and not a member of the more commonly known Mola mola ocean sunfish species as originally thought, according to researchers from Hiroshima University.Bony fish have skeletons made of bone rather than cartilage, as is the case for sharks or rays.

In the study, published in the journal Ichthyological Research, researchers led by Etsuro Sawai referred to more than one thousand documents and specimens from around the world - some of which date back 500 years.

Their aim was to clarify the scientific names for the species of the genus Mola in fish. They also solved a case of mistaken identity. The Guinness World Records lists the world's heaviest bony fish as Mola mola, researchers said. However, Sawai's team found a female Mola alexandrini specimen of 2,300 kilogramme and 2.72 meter caught off the Japanese coast in 1996 as the heaviest bony fish ever recorded.

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.

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, researchers said. Specimens can measure up to three meters (total length), and many weighing more than two thousand kilogrammes have been caught.
Instead of a caudal fin, sunfish have a broad rudder-like lobe called a clavus, they said.