I just recently treated my tank for Columnaris earlier this week (my Gourami's sores healed right up and the white growth went away!) with APIs medication Furan-2. Now at first search, we didn't know that the medication could not be used in the tank if invertebrates were present, so for the first day of medication the snails were in the 10 gallon tank (two mysteries and two nerites). Once we did more research we got really nervous and removed the snails from the tank into a quarantine container for a few days. The smallest of the snails didn't make it but the other three seemed to recover. Once the treatments were over we places the snails back in the tank, but one of the snails seems to have a white-ish goo following him. Is that the columnaris we just treated the tank for making it's way back into the tank from the untreated snails? Or is it just something snails do?