I've been battling fin rot in a 20 gallon with guppies and zebra danio for 2 months. The original source was the guppies, who had their fins nipped in the 45 gallon prior to being moved over. I tried a month of near continuous water changes, it just kept getting worse. So the last month has been Maracyn, Maracyn 2, Ich-X, Paracleanse. I've seen improvements in some fish, including some really good fin regrowth in one of the worst affected guppies. The danios have even started breeding again, which I thought was a good sign. But today I noticed a huge new tear on one of the danios, two days after finishing with Maracyn. I am at a loss for what to do now. But the icing on the cake, I noticed a white spot in the 45 gallon today, on a black skirt tetras tail. I managed to keep it from spreading to that tank for 2 months, but now it has. It's just one small spot on a male skirt tetras tail, probably where another male nipped him. Should I dose the tank with Ich-x right now? My QT tank is occupied. I am on the verge of giving up and shutting the tanks down. Any and all advice is appreciated, thank you.