Quick Answer: The ocean sunfish, or mola mola, is the heaviest bony fish in the world, weighing up to 2,200 pounds. Shaped like a giant swimming head with no true tail, sunfish are famous for basking sideways at the ocean’s surface to warm up after deep dives for jellyfish. They’re occasionally spotted off the Southern California coast, often surprising whale watching guests expecting only whales and dolphins.
Every so often, a Harbor Breeze crew member spots something on the water that isn’t a whale or a dolphin at all — and gets just as excited. The ocean sunfish, or mola mola, is one of the strangest and most memorable surprises out there, and it’s a genuine record-holder in its own right.
What Makes the Ocean Sunfish So Strange-Looking?
The ocean sunfish looks less like a typical fish and more like a giant swimming head. Its flattened, disc-shaped body has no true tail fin; instead, a rounded structure called a clavus serves as a rudder. Adults can grow up to 10 feet tall and wide, with tall dorsal and anal fins that sweep back and forth to propel them through the water.
How Big Do Ocean Sunfish Get?
Ocean sunfish can weigh up to 2,200 pounds, making them the heaviest bony fish in the world. For comparison, the whale shark is the largest fish overall, but it’s cartilaginous rather than bony, which is why the sunfish holds a separate, equally impressive record.
What Do Ocean Sunfish Eat?
Jellyfish make up a large part of the ocean sunfish’s diet, though they also eat small fish, squid, and zooplankton. Because jellyfish are low in nutrients, sunfish have to eat huge quantities to sustain their massive size, often diving hundreds of feet into cold water to find enough food.
Why Do Sunfish “Bask” at the Surface?
After a deep, cold dive, ocean sunfish are often seen lying flat on their sides at the surface, soaking up the sun. This basking behavior helps them warm their body back up after foraging in colder water, and it also gives seabirds and small fish a chance to pick parasites off their thick skin.
Are Ocean Sunfish Dangerous?
Despite their massive size, ocean sunfish are completely harmless to humans. They’re slow, docile swimmers with no interest in boats or people, making a surface sighting a purely fun and harmless surprise.
Spotting Ocean Sunfish Off Southern California
Ocean sunfish sightings are unpredictable, but they do happen off our coast, especially in warmer months when jellyfish are more abundant. They’re one of many surprises alongside the marine life covered in common marine mammals and California’s kelp forests.
You Never Know What You’ll See
Whales and dolphins are the headliners, but the ocean sunfish is proof that every trip has the potential for a surprise. Check our whale sightings report, then book a Long Beach whale watching tour with Harbor Breeze Cruises to see what’s out there.