It appears my young white angel fish has tail rot. I had a blue crayfish in the tank because my husband had to have it but I finally talked him into letting me get rid of it since he got two of my other angel fish. I'm not sure if he had nipped it off or what. The fins just look frayed and I notice they get shorter. I tried melafix and stuff like that but now I have to be careful because I have a ghost knife in the tank as well. I have 4 angel fish (2 adult 2 juvenile) and the young white one is the only one I am having an issue with. Suggestions?