Hi, my name is Mary and I have, at this time just one goldfish. We have a 20 gallon tank and I try to really take good care of it. Some time ago I noticed that our goldfish, Lucy, had this cottonie like stuff just under her right eye. Went to the pet store and they told me she had a fungus. I bought medication for this disease and followed the instructions. I treated the tank and asked at the pet store when this cottonie stuff would go away. They said it might take about a month. This was about at least 6 months ago. I have treated the tank 3 times with this medication. She seems to be fine, but still has this cottonie stubstance. How do I get rid of this?