The heaviest bony fish in the ocean is the Sunfish (Mola mola) which has been recorded weighing 2 tonnes (4,400 lb) and measuring 3 m (10 ft) from fin tip to fin tip.

Mola mola actually comes from the latin meaning millstone. Sunfish are found in all oceans in tropical or temperate climates and feed on zooplankton, small fishes and algae. For reference, sharks and rays for example are cartilagnous, not bony as in the case of the Sunfish.