It is not allowed to raise fish with pure water. Pure water can't be used to raise fish. Pure water is too clean, and there is no oxygen in pure water, which easily leads to fish breathing difficulties and death due to lack of oxygen. In addition, there are no minerals, trace elements and other substances needed by fish in pure water. Tap water, well water and river water are all used to raise fish, but you must contact chlorine in advance and then set K before you can raise fish. Pure water, referred to as purified water or pure water for short, refers to water without impurities, which is generally sealed in a container, colorless and transparent, and can be directly drunk. Tap water, well water and river water are used to raise fish. It is best to use exposed tap water to remove chlorine in water, which is mild and suitable for fish to survive. Well water and river water have choices, but they can only be used after exposure. Fish farming is a technical activity, and chlorine, minerals and minerals in water are suitable for fish to survive.