I would think that the natural mineralization is beneficial for some fish. If it is, like April say, good for growing discuss that it can not be that hard. Many years ago, I was to keep quite healthy Malawi fish as well as some Central American cichlids with well water is Kelowna. I would think that coastal well water is not nearly as hard or alkaline as interior reservoir water or well water, but that is a guess. It might be really good for your fish