I have 2 albino Cory Catfish and had 3 goldfish, one goldfish ended up getting finrot and I took him out as soon as I noticed and put him in a 1.5 gallon bowl and treated him with medicine for finrot and did daily water changes and he ended up passing away. Now my one Cory Catfish has finrot. I transferred him to the bowl and gave him medicine the first day and then did daily water changes after that and completely cleaned out my big tank so my other fish don't get it. The Cory Catfish has improved over the course of a week, he's swimming so much now and eating. How long should I wait to transfer him back to the big tank?