This family of sturgeons is represented by the Polyodon spathula and the Psephurus gladius. The former lives in the Mississippi Basin.It can live for more than 30 years, reach 3 metres in length and weigh 100kg. Its eggs are a beautiful grey-green.  Previously victim of over-exploitation in Tennessee, its fishing is now strictly regulated. The Psephurus gladius lives in China's River Yangtze. It also grows to a maximum 3 metres, but can weigh up to 300kg. It's the largest Chinese freshwater fish. Even if this species iis protected, it is still in danger of extinction and the attempts at farming have not yet been successful.