I have used it repeatedly since I collect all my plants and fish locally. Inevitably I pick something up that has Ick. At the recommended treatment levels, It has never hurt my wild caught snails. My favorite TX Cichlid just died (of old age) and I had to go out and pick up a couple more. In the process, I picked up a few other spps as well along with some crayfish. I also picked up a very small yellow bullhead who (of course) has Ick. I have not noticed it on any of my other fish yet so I raised the temp tonight to 78 and treated the whole 110G tank with coppersafe. Hopefully the crayfish will survive, we'll see. I've never treated a tank containing crayfish so I don't know. I've read in some places that coppersafe may not hurt inverts with exoskels. I guess I'm experimenting and learning.
NOTE: I always take out the bio wheels from my two Emp. 400's and put them in a water storage tank. The importance of beneficial bacteria cannot be over stated and I don't want to loose mine.