There are 19 species of eels*** worldwide, distributed in the Pacific, Atlantic, and Indian Oceans. Except for the European eel and the American eel, which are distributed in countries on both sides of the North Atlantic, the rest are distributed along the Indo-Pacific. There are two species along the coast of mainland China, i.e., Japanese eels and Anguilla anguilla, and there are two other species offshore of Taiwan, i.e., two-color eels and Celebes eels, in addition to Japanese eels and Anguilla anguilla. In addition, the Australian eel and the broadfin eel are mainly found off the coast of Australia. The most important species cultured in Asia is the Japanese eel, followed by the Anguilla anguilla. Anguilla anguilla is mainly distributed in the south of the Yangtze River in China, Zhejiang, Fujian, Guangdong, Hainan and Taiwan and other provinces along the coast, due to the small resources, the breeding is not common, at present, only in China's Hainan Province and Taiwan Province have part of the breeding. Japanese eel is more widely distributed, distributed in the north latitude 20 ° ~ 40 ° Pacific western coastal countries, such as North Korea, Japan, China, the Philippines, Thailand and so on. In China from the Gulf of Tonkin in the south, north to Bohai Bay, east to Taiwan, the west can migrate to the Yangtze River and the upper reaches of the Yellow River Jinsha River and Weishui area. North of the Yellow River is limited to the lower reaches of coastal rivers or estuaries.

The eel belongs to the downstream migratory fish. Spawning in the sea, the baby fish for the transparent leaf eel, spring, when the baby fish developed into young eel, swarms of swim in the river, in the tributaries or lakes in the fertilization, after maturity, the river swim down to the sea to reproduce, to eat small fish, crabs, shrimp and aquatic insects mainly. General night activities. Rapid growth, meat tender and fat, nutritious. Now artificial culture.

Eel body elongated, the front end of the cylindrical, backward gradually flattened. The head is long and pointed blunt, the eye structure is complex, with daytime color observation, nighttime light-sensitive two roles, the kiss is prominent, the mouth is large, anterior, upper and lower jaws and plow bones are banded arrangement of fine teeth. The gill pores are small and located below the base of the pectoral fins. The skin of the eel is composed of the epidermis and scales, and the epidermis is divided into epidermis and dermis, the scales are small and oval, buried under the dermis, arranged in a mat-like pattern, and the whole body has well-developed subcutaneous mucous glands. The eel has a lateral line system in the center of both sides of the body, which plays a sensory role. The olfactory nerve of the eel is especially developed, and plays an important role in the search for food. The eel does not have a tongue, but has a very sensitive sense of taste and uses the nerve endings in the mouth to recognize food. The eel's dorsal and anal fins are well developed and are connected to the caudal fin. The pectoral fins are rounded and short, the caudal fin is rounded and blunt, and there is no ventral fin. Depending on the length of its fins, it can be roughly divided into the long-finned type (the length from the anterior base of the dorsal fin to the anus is 9% to 17% of the fish's total body length) and the short-finned type (0-5%). Wild eels have a blue-gray dorsal surface and a pale white belly, while pond-raised eels have a blue-black dorsal surface and a white belly. However, with the difference in water quality and bait quality, or other environmental conditions, the body color of farmed eels varies slightly, such as brown, dark blue or black. Sexually mature parent eels in the descending river into the sea spawning, the side of the body is a metallic luster of the marriage color, the abdomen light purple.