Can anyone please help me out?

I have a (tall) 20 gallon tank with one adult angelfish, 4 different corys... well one is an Emerald catfish.

All the catfish are about 4 years old, I got them all around the same time. They have always been very healthy and everything has been just fine with them ...

I treated with Pima Fix (it's supposed to treat fungus) and it didn't do any good. Now my other Cory has the same thing.

I'm going to get sand for the tank to avoid anymore damage but I can't seem to fully treat the spots they already have. I just don't know what else to do.

So what should I do? It doesn't seem to be going away after using pimafix. Do I need to use melafix along with it? Is all that stuff safe for my neons?

My cory has had a white spot on his nose for at least two or three weeks now. At first I thought maybe it was just from rubbing his nose on the gravel. So we kept the water real clean and just kept an eye on it. Well after a few days it started to look a bit fuzzy to me. So we started treating with ...