Ocean Sunfish Facts - Animals of the Ocean

A close-up of an ocean sunfish.
A close-up of an ocean sunfish.

Occasionally known as the common mola, the ocean sunfish is the heaviest bony fish. Bony fish are distinguishable from cartilaginous fish based on what makes up their skeletons. Mature adults of the species usually weigh anything between 545 pounds and 2,205 pounds with an average length of 5.9 feet. From one fin to another, their average length is around 8.2 feet. The largest ocean fish was ten feet wide and weighed around 5,000 pounds.

Physically, the fish resembles a fish head with a tail and a body that is horizontally flat. With a dorsal fin that resembles that of a shark, the ocean sunfish is easily mistaken for a shark while swimming close to the water surface. On the subject of color, adults may be grey, white, brown, or spotted. The dorsal region is typically darker than others.

Habitat and Behavior

Ocean sunfish live in waters all over the planet and major oceans such as the Atlantic, the Indian Ocean, and others. The genotypes that live in the Pacific and the Atlantic show greater variations than those genotypes residing in the southern and northern hemispheres.

Ocean sunfish prefer to spend their days in deep waters, especially in warmer waters such as in the Gulf of Mexico. The fish are likelier to spend more time on the surface of the ocean at night. Studies have shown that they possess the capability of swimming at speeds of 2 mph and can cover up to 16 miles in a day. More often than not, they will be swimming at depths of 2,000 feet, making it extremely difficult to observe the fish with the naked eye.

Sunfish prefer waters that are warmer than 50 degrees Fahrenheit. They will come to the surface and expose a side of their body to the sun, particularly after being in deep, cold waters. Furthermore, they are mostly solitary creatures but they have been observed in pairs.


Sunfish are ravenous predators that hunt, kill, and feed on other fish. The most common items on their menus include siphonophores and jellyfish. While the two are the preferred food, sunfish can also be classified as generalist predators who do not mind feeding on small fish, crustaceans, squid, and salps. On occasion, eelgrass may also be part of the diet. Sunfish are not dangerous to humans.


The reproduction of sunfish is not widely understood. The little information available shows that spawning regions are mostly in the Atlantic, the Pacific, and the Indian Oceans. One known fact is that one sunfish can lay an incredible 300 million eggs at a time. The eggs are relatively small and are fertilized externally. This higher number is a mechanism that ensures the survival chances are increased due to the high amounts of predators.

The larvae hatchlings measure a measly 0.1 inches and weigh less than a gram. If they survive to adulthood, the fish would have grown at least 60 million times what their larvae size was. In confinement, they have a lifespan of up to ten years. Their lifespan in the wild is unknown.


More in Environment