Ocean Sunfish (Mola mola) are the largest bony fish in existence, measuring up to across and weighing lbs. Their favorite food is jellyfish. They have no tail. At night they often come to the ocean's surface for hours at a time, barely moving.
They used to have one of these at the Monterey Bay Aquarium, it was my favorite thing to see there. It amazed me how something so large and unlovely could move with such amazing grace and fluidity. Such joy!