Family Polyodontidae Polyodon and Psepherus spp.

• two species of paddlefish: the Chinese swordfish and the American paddlefish
• ancient fish with many primitive characteristics which can be seen in their heterocercal tail, shark-like body plan and skeleton composed of cartilage
• the Chinese paddlefish grows to a maximum three metres
• the American paddlefish grows to two metres.

• The American paddlefish is located in the Mississippi, Missouri and Ohio Rivers and their tributaries.
• The Chinese paddlefish is native to the Yangtze River and tributaries.

• predominately found in freshwater although the American species can tolerate brackish waters
• prefer large deep rivers with slow-flowing turbid water
• spawning areas need to have gravel or sand beds.

• The American paddlefish feeds mainly on zooplankton, which it filters from the water column, but may also consume benthic crustaceans and worms.
• The Chinese paddlefish is a top level predator and is exclusively piscivorous.

• undertake a spawning migration in spring when conditions are perfect, which may only be every two or three years
• females release eggs into the water which stick to the substrate
• no specialised nesting structure is made, nor is any parental care demonstrated.

• extremely large fish which would compete with native fish for food items and habitat
• the American paddlefish may change water clarity through benthic feeding.