A pair of Chinese sturgeons swims in the Beijing City Aquarium in China. Capable of weighing half a ton and growing to 16 feet (5 meters) long, this freshwater leviathan is one of the largest sturgeon species on Earth. River damming in China has caused its numbers to plummet, and it is listed as an endangered species.
The world's largest freshwater fish are losing the fight for survival as pollution, overfishing, and construction threaten the rivers and lakes they call home.