Changyu is a famous specialty of Xiamen, commonly known as crocodile bugs, its main place of origin in Xiamen City, Tong'an County, Liu Wudian, and because of Liu Wudian sea islet there is a Wenchang Fish Pavilion and so named. Liu Wudian is the world's only Wenchang fish farm; in recent years in Xiamen, the eastern part of the island between the village of Qianpu and Datan, and found a new fishing ground of Wenchang fish.

Xiamen amphioxus body shape is small, only three or four centimeters to five or six centimeters long, nearly 10,000 tails per kilogram, the whole body is translucent, the head and tail of the two pointed, also known as the foreign "double pointed fish", is a high-level edible protein snacks, its protein content of 70%, and contains a variety of inorganic salts and iodine, tender meat, flavor Qingjin sweet, made of dried products, can be stored for a period of one year, and can be stored for a period of two years, and can be used in the food industry. The meat is tender and has a sweet and refreshing flavor, and can be stored for a year if made into a dry product

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