Family Polyodontidae - Paddlefish Family
Paddlefish have a skeleton made of cartilage, even though they are considered bony fishes. The mouth is located on the bottom of the paddle-shaped snout. Two small barbels are found on the bottom of the snout as well.
paddlefish (Polyodon spathula)
Photo © Jennifer Idol/Engbretson Underwater Photography
Features and Behaviors
Although its average weight is two pounds, the paddlefish may reach 160 pounds in weight and a length of seven feet. This fish may live 20 to 30 years. It has a flat, broad, paddle-shaped snout, a long, tapered, gill cover and no scales except for a patch on the upper lobe of the forked tail. The snout contains an elaborate system of sense organs. The body is gray to blue-gray on the back and sides with a white belly. The skeleton is mainly cartilage. Historically, the paddlefish has been used for food and the eggs for caviar.
The paddlefish lives in large rivers, preferring slow-moving water over four feet deep. For spawning it requires a large, free-flowing river with gravel bars that will remain flooded for the duration of the spring spawning period. This fish swims continuously in open water and may leap out of the water. It does not seem to have a home range and may swim hundreds of miles. The paddlefish reaches maturity at age seven. It spawns in April or May. The eggs are scattered over a silt-free sand or gravel bottom in a large, free-flowing river. Floods of several days' duration are needed for spawning to be successful, as the gravel where the eggs are deposited is normally out of the water. Eggs are sticky and attach to objects on the bottom. Eggs hatch in about nine days. The paddlefish feeds on microscopic crustaceans and insect larvae it filters from the water as it swims about with its mouth open.