The eel is a migratory fish, in the spring of every year, the young eel from the sea into the estuary, the male eel usually grows up in the mouth of the Yangtze River, while the female eel goes upstream into the Yangtze River trunk, tributaries and lakes connected with the river, and some of them even go upstream to the upstream of the Yangtze River, which is 1,000 kilometers away from the river, to live in the upper reaches of the Yangtze River. Although this fish lives and grows in fresh water, it spawns and breeds in the sea. They grow and fatten in rivers and lakes, and mature at about five to eight years of age. The eel's gonads do not develop well in freshwater and can only stay in the early stages. In February and April, eels with a body length of up to 45 centimeters or less are often difficult to distinguish between sperm and ovaries. Eels whose gonads are about to mature will descend down the river in the fall and winter season and enter the sea before they gradually mature, and their body color will become blue-black, with a layer of golden luster on the side of the body, and the bases of the pectoral fins will become golden, showing the so-called matrimonial color. Sexually mature female and male eels arrive at the spawning grounds in pairs, where they spawn and reproduce. However, after spawning, the parent eels are exhausted until they die.

The young eels that hatch on the _ day of hatching go through a metamorphosis and grow long and sharp serrated teeth, called white eels, also known as glass eels because of their transparent bodies. By the third day after birth they swim into coastal estuaries. Usually in May-June in the coastal - belt can be found in this white willow leaf-shaped transparent fish, with the waves, this is the young eel. When these juvenile eels enter the estuary in groups, they have changed from flat leaf-shaped to cylindrical, and start the second stage of their life in fresh water. When the eel enters fresh water for about two weeks, its body color changes to black, and it has already taken the form of an adult eel, which is called a black eel. They continue to swim against the current and reach inland rivers, streams, lakes and ponds. To aquatic insects and snails and other food, generally live in fresh water 5 lO years, fattening up, the body reserves a lot of fat, more than 2O% of body weight. In the natural environment, the eel male and female ratio of 6:4, female individuals longer, can grow to lOOOg, the maximum body length of 75 centimeters, male individuals smaller, the largest individual up to 6l centimeters.