The ocean sunfish (Mola mola) is the largest of all bony fishes and can reach an astonishing 3,000 pounds or more; the world record is 5,071 pounds. These gentle giants are also hugely popular with Aquarium visitors.

 Aquarist target feeds an ocean sunfish, from the catwalk over the Outer Bay exhibit

Although we've successfully displayed ocean sunfish for more than 20 years, their lives in the wild are shrouded in mystery. In 2008, we initiated a comparative behavioral research project to gain greater insight into ocean sunfish behavior within Monterey Bay and beyond. We know that they are seasonal visitors to bay waters, but where do they travel when they leave? How frequently and how deep do they dive? Is swim behavior affected by time of day or season? Do they demonstrate temperature preferences?

Through a program of tagging and tracking via satellite both wild ocean sunfish and captive fish that have been released back to the wild, coupled with ecological data analyses, we're trying to find answers to these and many other questions about these bizarre and intriguing fish.

Our aquarists are also continually studying the growth and consumption behaviors of our ocean sunfish on exhibit. The results are helping inform our animal care management strategies and improve our techniques, providing us with a better understanding of how to keep our captive fish healthy and thriving.