Hi all, We have a Betta Sorority tank (20 gal, heated, filtered, water changes once a week) consisting of 5 girls. One of them sustained a relatively large injury from nipping on her fin recently. Seeing as 2 of the Bettas were added within the past few weeks after the most aggressive female was removed from the tank, we chalked it up to a new hierarchy being formed and didn’t worry about it. Today I was looking at her very closely because she was acting lethargic, floating alone at the back of the tank, and noticed that her other ‘fin’ was actually a stringy fungus. After researching it on various Betta forums, i believe it is cotton wool syndrome. We immediately removed her from the Sorority placing her alone in a temporary quarantine tank with about 50% water from the 20 gal and 50% conditioned new water, and 1 tbsp of aquarium salt. None of the other fish look affected. Is there anything else we can do to help her? Or does anyone have any suggestions to what this may be if it is not cotton wool syndrome? Unfortunately we cannot snap a clear picture of the fungus right now but I will try to post one tomorrow. Should we be worried about the rest of the fish in the 20 gal?