Among the clean freshwater fish, the giant salamander is the first, and the giant salamander generally needs to be cultured in running water, followed by mandarin fish and perch, the third should be carp and crucian carp, which eat feed and living organisms, the fourth, tilapia and snakehead, which have mixed diets, the fifth should be grass carp, mainly eating aquatic plants, and the sixth should be catfish, which can survive in sewage, and China people generally do not eat catfish in the past.