Most Bizarre Fish You’ve Ever Seen? A diver swims with a huge ocean sunfish, or Mola mola, off the coast of San Diego. They are the largest of the bony fish and often get mistaken for sharks due to their dorsal fins. They feed on jellyfish and plankton and are curious of humans, as seen in the photo. One threat to molas is drift nets, which they often get caught in, and garbage such as plastic bags that they mistake for jellyfish, their favorite food.