To treat Ich, you need to add pond salt to the water. You add salt to provide essential electrolytes to help fish reach peak coloration and vitality. It also helps gill function, reduces stress, improves osmoregulation, and speeds disease recovery.
It is best to think of pond fish in the same way that one would think of fish in an aquarium. Both are in a synthetic environment that is on a closed circuit, meaning the same water is simply recycled within a designated area.