Seven-star eel, also known as star eel, sea eel and sand eel, has a long cylinder shape, generally 30-60 cm in length and 300-700 g in weight. It has no scales, smooth skin and a complete lateral line. There are a row of white punctate sensory holes along and above the lateral line, which are distributed in China, North Korea and Japan, and belong to the species of Guangwen and euryhaline.