Untreated loach contains a lot of parasites as well as bacteria. The way to deal with the loach: first catch the loach in the water to feed for a period of time, to remove sand and other impurities, and then put the loach into the basin, sprinkle salt, cover the lid, after a while with water to wash, and then cut open the loach, remove the viscera, wash with water to remove most of the parasites and bacteria in the body of the loach.