i dont know if he's a boy, but ill just say he. he's a tetra, i dont know what specific kind, only that he's silver and has a red pattern/dot above his eyes. used to be in my 20 gallon tank, but the other fish started picking on him. most of his fin were gone, and there was a cut in his side. i put him in my five gallon tank instead and the fish there arent bothering him. his fins have regrown, but there is a gaping hole in his side. it looks painful, but he is swimming fine. what should i do? is there any medicine i can give him to make it heal? thank you!! any advice will help =]