Should I add some fin rot & fungus control to my other fish even though they're not ill?

I have two 10 gallon tanks in my room, in one there's two small goldfish and in the other there's two Shubunkins. Recently, my two goldfish became infected with fin rot and cloudy mold began growing in the bottom of the tank. I pick up some fin rot & fungus treatment the next day, but now I'm debating on putting it in the shubunkins tank as well, just as a precaution. Should I add it or not?