Either of two species (family Polyodontidae) of archaic freshwater fishes with a paddlelike snout, wide mouth, smooth skin, and cartilaginous skeleton. It feeds with mouth gaping open, gill rakers straining plankton from the water. The American paddlefish, or spoonbill (Polyodon spathula), is greenish or gray and averages 40 lbs (18 kg); it lives in the open waters of the Mississippi basin. The other known species (Psephurus gladius), a larger fish with a more slender snout, inhabits the Chang (Yangtze) River basin. The flesh of both species resembles catfish; the roe can be made into caviar.