As part of its popular National Geographic Live! speaker series, the Perot Museum hosted monster fisherman and aquatic ecologist Zeb Hogan on March 2. His presentation, Zeb Hogan: In Search of River Giants, took guests along on his international excursions where he’s encountered some of the world’s largest freshwater fish – longer than six feet and more than 200 pounds. Many of these giant swimmers, known as megafish, face extinction, which could in turn threaten freshwater ecosystems and the livelihood of millions of people. In an effort to bring awareness and understanding of these water-dwelling behemoths, Hogan has been traveling the world – spanning six continents – to help these critically endangered species.