Catfish is dirty because of its internal organs. Because it can survive in human feces, some fish farmers deliberately feed them with human or pig feces. Living in a harsh environment for a long time, catfish are prone to accumulate toxic substances, such as heavy metals, which cannot be eliminated no matter how high-temperature cooking.

Catfish, also known as Hu He, is characterized by its scaleless body, slippery body surface, flat head, wide mouth and four whiskers on its upper and lower jaws. Widely distributed, mainly produced in the Yangtze River and Pearl River basins, the best edible season is from mid-spring to mid-summer (April to July). Catfish is a carnivorous fish with tender meat, delicious taste, rich in protein and fat, and rich in nutrition, especially suitable for people with weak constitution and malnutrition.