I have a 6inch arrowanna with fin rot pretty bad. i did the marclyn(blue box with 2 small fish on the front, packets of white powder) or whatever treatment twice. after the first time the fins looked better but got worse a week or so later. the second time there was no difference. im positive i did the treatment right both times but for what ever reason didnt work. does anyone of some other ways to treat fin rot? thanks.