Ocean Sunfish - Maximum mass (tonnes): 2.3

The Ocean Sunfish or common mola (Mola mola) is one of the two heaviest known bony fish in the world, the other being the southern sunfish (Mola alexandrini) of the same genus. The average adult weighs 247 to 2,000 kg (545 and 4,409 lb). The species is indigenous to both tropical and arctic glasses of water. Its main body is flattened laterally, and its head and tail resemble fish. When their dorsal and ventral fins are extended, sunfish can reach heights of as much as their length.

Small fish, fish larvae, squid, and crustaceans make up the majority of the diet of sunfish, which are generalist predators. Thought to be the main source of food for sunfish in the past, sea jellies and salps now make up only 15% of a sunfish's diet. Females of the species can lay up to 300,000,000 eggs at once, more than any other known vertebrate. With their enormous pectoral fins, tail fin, and body spines that are not typical of adult sunfish, sunfish fry resembles little pufferfish. Although adult sunfish have few natural predators that can harm them, sea lions, killer whales, and sharks will eat them. Some regions of the world, such as Japan, Korea, and Taiwan, prize sunfish as a delicacy. Regulations prohibit the sale of fish and fisheries products originating from the Molidae family in the European Union.