Paddlefish (family Polyodontidae) are primitive ray-finned fishes. The paddlefish can be distinguished by its large mouth and its elongated snout called a rostrum (bill). These spatula-like snouts comprise half the length of their entire body.Paddlefish (family Polyodontidae) are primitive Chondrostian ray-finned fishes. The paddlefish can be distinguished by its large mouth and its elongated snout called a rostrum (bill). These spatula-like snouts comprise half the length of their entire body.