some people use salt some use heat and some use ich treatment......when i had this prob in one of my tanks ich infected alot of my fish so i search n asked for help too.....this is what i did i used ich treatment and killed off half of them with this treatment......could not get rid of ich.......so i learned that raising the water temp 85 degrees for a week killed off the ich and everythings has been great since then, just remember to research anything you do.