Sorry if we are not supposed to ask about other fish here. In my 30 gallon I had a problem with my bronze corys. They had white raised blotches and fin rot. I was told to use Maracyn and Maracyn 2. This took care of the problem. Today, I noticed one of the guppies has a white fuzzy spot on her head. It actually looks like a tiny piece of fuzz just fell there from someplace. She is acting and eating normal. The white spots that were on the corys were not fuzzy. I have no clue what treatment to use. All I have on hand is Maracyn - TC for popeye, gill disease and fin rot and I also have a bottle of penicillin in gel format. Will either of these help? I can't stand to see a fish in poor health, but this tank has been nothing but a pain in the butt since day one. We have the normal live bearer die off and I have stopped replacing anything. Eventually I plan on taking over this tank and have no live bearers. It is my daughters tank and she not only has lost interest, she is moving in a month to an off campus apartment. As of right now, all that is left in the tank is 2 male and 2 female guppies, one platy, 6 neon tetras, 5 cory and one BN. After my demasonis move out of my 10 gallon, I would like to put the cory and neons in it. I would like to add the bn to my 75 gallon malawi. That just leaves 4 guppies and one platy to deal with. I don't know the actual life span of those fish but they are over 2 years old. To be honest, I am tired of spending a fortune to keep these fish alive. Sorry for my long winded rant. She throws a fit when I talk about getting rid of them. (lfs not killing them) yet I pay for the meds and clean the tank.