No... even with water conditioner your spring water is far lacking what is needed. Tap water, whether you believe it's gross or not, is healthier and safer to use over spring, filtered, distilled water.
Slowly acclimate him to tap water by doing partial water changes over a few days time with tap water in the tank. Spring water is not sufficient, and conditioner removes and binds elements in the water, but won't give the water what is needed. Nutrition comes from food, minerals is what the spring water lacks and is needed by the fish.. people want to believe what is good for us, is good for the fish.. such as spring water.. but they are fish and their needs are different.