Paddlefish is the common name for the ray-finned fish. It is characterised by an elongated, paddle-like snout with minute barbels, a large mouth with minute teeth and along gill rakers. There are only two modern species of these fish, i.e. the plankton-feeding American paddlefish (Polyodon spathula) and the piscovorous Chienese paddlefish (Psephurus gladius). Paddlefish are not closely related to sharks. However, they have several body parts that resemble those of sharks such as their skeletons and deeply forked heterocercal tail fins. Paddlefish provide important economic, ecological and aesthetic values. During the last century, paddlefish and sturgeon have been commercially exploited for their eggs (roe) called caviar. Paddlefish and sturgeon are two of the most important fish for freshwater caviar. Their unique shapes and large sizes also add to the joy of nature for humans, including sport fishing. However, exploitation and habitat changes, among other factors, have significantly reduced the population of paddlefish. Why does the population of paddlefish decrease?​