Ralph, the 7-meter whale shark who entranced audiences at the Georgia Aquarium, has died of unknown causes. Ralph was one of four whale sharks (Rhincodon typus) in the aquarium. It's the only facility in the United States, or indeed anywhere outside of Asia, that maintains a population of the world's largest fish. The whale shark is capable of growing to 15 meters or more. The aquarium's other three whale sharks, Norton, Alice, and Trixie, appear fine.