My guy has been battling fin rot. Went away, came back, went away, regrowth, came back. Now his fins look terrible and he has this growth on his tail in the gray patch. What is it and what can I do for him? Also, i put a malaysian trumpet snail in the tank the other day. Dont know if that would contribute to this? He's in a heated filtered 5 gallon. Ammonia .25, nitrites 0, nitrates 5, 79f., 7.9 ph I posted in every group I know. I have people saying I shouldnt use prime, people saying to use melafix, do 90% daily water changes forever. What do I do?