The ocean sunfish is a large, grey-blue, oval-bodied fish with prominent and powerful dorsal and anal fins, but no tail fin. This gives the sunfish the appearance of only being "half a fish."  Despite its unusual appearance, it is an active swimmer and is highly manoeuvrable.

The Aquarium does not currently have an ocean sunfish on display. This information is preserved as a reference.

They are the largest bony fish in the ocean - growing up to 3m in length and approximately 2000kg in weight.

Ocean sunfish have relatively small mouths, with fused teeth that give it a parrot-like beak. The beak is internal and hidden from view except when feeding. They use this beak to feed of jellyfish and salps, but will opportunistically feed on squid, fish, crustaceans and brittle stars.

Their skin is covered with a tough armour of dermal denticles, similar to that of sharks and rays.

Sunfish get their name because of their habit of basking on their sides on the ocean’s surface. This is done to help regulate their body temperatures, as these fish can dive to well over 600m - into frigid waters.

Ocean sunfish are found in all the oceans of the world, excluding the icy polar seas.

Read more about sunfish, and our work with them, here.

Species Facts

  • Very little is known about Mola mola - for example, the early stages of their lifecycle, as well as their ages remain mysteries.
  • Sunfishes are so called because of their habit of drifting at the surface as if basking in the sun.
  • Sunfishes do not have tails as other fishes do – the caudal (tail) fin has been replaced by a rudder-like structure. The ocean sunfish has a rounded, wavy rudder. The sharptail’s rudder, as the name suggests, has a distinct point.
  • Sunfishes are not considered edible as they consist mainly of cartilage and gristle and their flesh is soft and insipid. Also, the skin is extremely rough, similar to sandpaper in texture.
  • They are the most fertile of all fishes, producing up to 300 million tiny eggs.
  • The name ‘mola’ is derived from the Latin word for millstone because of their similar shape.