Physical Description

  • Rounded, truncated, bullet-like shape, extremely flattened laterally (side-to-side).
  • Very large dorsal (top) and pelvic (bottom) fins, very small caudal (tail) fin and pectoral (side) fins.
  • Silvery coloration with whiter belly, and very rough skin.
  • Can be 14 feet tall, 10 feet wide, and weigh up to 2.5 tons! 
  • Appearance of being half of a fish.
  • Teeth fused into almost a beak; cannot fully close mouth.
  • Baby sunfish are born as only 2 mm round circles, with large spikes around the perimeter. They grow very fast, up to 2 pounds per day.


  • Temperate and tropical regions of the Mediterranean, Atlantic, Indian, and Pacific Oceans.
  • Common off the coast of southern California, Indonesia, the British Isles, New Zealand, the southern coasts of Africa, the Mediterranean, and in the North Sea.


  • Lives in the open ocean mainly, but sometimes goes in kelp beds and coral reefs so they can be cleaned by other fish.
  • Swim right at the surface where their large dorsal fin is often mistaken for a shark.


  • Ocean sunfish can produce more eggs than any vertebrate on Earth!
  • They can lay 300 million eggs in a single breeding season, and are thought to spawn multiple times per season.
  • Their eggs are very small, with an average diameter of 0.05 inches.
  • Spawning is thought to occur between August and October.


  • Mainly eat jellyfish and gelatinous zooplankton (like siphonophores, salps, and ctenophores).
  • Also eat small fish, sponges, squid, eelgrass, eel larvae, and algae.


  • Large sharks and California sea lions.

Interesting Facts

  • Mola is latin for millstone, referencing their rough round appearance. “Sunfish” references their habit of basking in the sun. In many European languages they are called “moonfish.” In German they are called “swimming head” and in Chinese they are called “toppled wheel fish.”
  • Ocean sunfish are the heaviest of all the bony fish! Some sharks and rays can weigh more than 2.5 tons, but they have cartilage, not bones.
  • Ocean sunfish can become so infested with skin parasites that they will leap 10 feet in the air to try to shake the parasites off, and they will invite small fish and birds to come eat the pests off their skin. 
  • Ocean sunfish can get caught in drifting nets, and often choke on plastic bags, thinking they are jellyfish. You can help protect them by not littering plastic into the ocean.

Sources: National Geographic; Smarter by Nature;; FishBase; PADI

Photo: Howard Hall