I have a rosy barb whose tail is infected. I came home one day and saw that where her caudal fin meets her body was very bloody. I think she might of got bit, most likely by my rainbow shark. Now two days latter her tail is all swollen, white and puffy. I am not sure what to do to help her. My sick tank is currently being used to raise some baby rosy barbs, and I do not have a ton of money to go buy medicine. Any advice or if any one knows of cheap medicine that would help, that would be great.