Hi. This looks like a great forum. I have Silver Dollars and 4 have shredded fins. I have never had fin rot in 30years experience of keeping fish. Thier tank mates are rainbows and corys. What is the best treatment for this please. I have done a week of medfex? For 7 days no difference. Any info you can give me would be much appreciated. No other fish in the tank has this. All maintenance of water changes ect are done weekly. Thank you.