Mola Mola

Ocean Sunfish (Mola Mola)

Mola mola, or sunfish, are the heaviest known bony fish, and can weigh >2000 lbs. Photo Credit: Billy Medwedeff, University of Washington; V14.

The largest bony fish in the world (and one of the strangest) is often seen near the surface in coastal Pacific waters. These laterally flattened fish look like a head without a tail, because the caudal (tail) fin has been replaced by a rounded “clavus,” creating the unique truncated shape. Adults have an average length of 1.8 m (5 ft 11 in) and a fin-to-fin length of 2.5 m (8 ft 2 in), and can weigh up to 2,205 lbs, and potentially get even larger. The maximum recorded size is 3.3 m (10 ft 10 in) in length, with a maximum weight of 5,100 lbs.

Unlike most fish, the sunfish swings its dorsal fin and anal fin in a characteristic sculling motion, and they can swim quickly when necessary. They feed on many types of small fish, squid, crustaceans, and jellies, hunting at depth before returning to the surface to bask. They often roll on their sides at the surface, sometimes allowing birds to land on their bodies (potentially removing parasites). Adult molas have few predators, but they are vulnerable to sharks, orcas, and sea lions.