I recently purchased 6 neon tetras and I’ve had them for a few days. Suddenly I noticed a white spot on one of their dorsal fins and didn’t think much of it, so I left it alone. BY THE NEXT MORNING (today), he was almost completely white and was barely alive so we flushed him. I have five more neons, three lemons, three jewels, and two bala sharks in my 75-gallon community tank. I believe the tetra was purchased with the infection. I have all live plants in my tank and feather rock. The parameters of my water is where it should be. I have a canister filter. Anyway, my question is, what should I do to prevent the spreading of the fungus to the rest of my fish? Should I treat the whole tank with Pima-fix? All of the fish are eating.