It is an animal of Spartina, Spartinaceae and Spartina. It is the largest of the seven species of finches and eels in North America, and can grow to 3 meters. The body is slender and the upper and lower jaws are also very long. The mouth is deeply cracked and has sharp teeth. The dorsal fin is opposite to the gluteal fin and located at the back of the body; Fat-free fin; Abdominal position of ventral fin. Each fin has no hard spines. Side line complete. The swim bladder has a swim bladder tube connected to the back of esophagus, which is multilocular and shaped like a lung. The wall of swim bladder is densely covered with microvessels, which can support gas metabolism. The body surface is covered with diamond-shaped hard scales, the vertebral body is concave, and the tail is almost curved. It is a low-grade bony fish.