Sunfish, in general are predators that consume largely small fishes, fish larvae, squid, and crustacean. Sea jellies and salps, once thought to be the primary prey of sunfish, make up only 15% of a sunfish's diet. Females of the species can produce more eggs than any other known vertebrate, up to 300,000,000 at a time. Sunfish fry resemble miniature pufferfish, with large pectoral fins, a tail fin, and body spines uncharacteristic of adult sunfish.

Adult sunfish are vulnerable to few natural predators, but sea lions, killer whales, and sharks will consume them. Among humans, sunfish are considered a delicacy in some parts of the world, including Japan, Korea, and Taiwan. In the EU, regulations ban the sale of fish and fishery products derived from the family Molidae. Sunfish are frequently caught in gillnets.

A member of the order Tetraodontiformes, which also includes pufferfish, porcupinefish, and filefish, the sunfish shares many traits common to members of this order. The ocean sunfish, Mola mola, is the type species of the genus.

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