Although the Mekong giant catfish may be the largest species of catfish, thousands of other species of catfish exist. According to John Lundberg, researcher with the All Catfish Species Inventory, 2,800 species of catfish have already been described and an additional 1,500 species may yet be discovered. "One out of every four freshwater fish, one out of ten fishes, and one out of twenty vertebratesis a catfish." Catfish are found on every continent except Antarctica and in fresh, coastal, and marine waters. They are perhaps the most ecologically and economically important group of fish in the world.