Copper sulfate is effective for deep-seated bacterial infectious diseases and parasitic diseases, but this kind of drugs are relatively toxic, so it is necessary to take out a medicine bath for treatment alone, and don't spill it all over the pool. Carelessness will lead to koi fish's massive death. If fish diseases occur or prevent fish diseases, you can spray quicklime in the pool, but you should choose a good method before, whether it is dry method, water fish or water fish, and think about it before you do it. Dry method is more thorough, large fish ponds generally use hairtail to bring water, and small and medium fish ponds can use hairtail to bring water.