hey guys i just got home today from being out of town.. i had a friend come by my house and feed my fish last night but he told me some thing was wrong with my fish... and i came home just now and saw it it looks like a buffy eye... like pink eye for fish? how do i treat it? and what am i suppose to do with him? do i take him out? can others get it from him? what casuses it? and what should i do... any help would be awesome thanks!

He could had been in a fight any mean fish could also be cemcicals

How long have you had the fish? What else is in the tank? How's your water quality? Do you have the lights on a timer, or were you relying on this friend to turn the lights off and on (ie. did the light cycle get "changed" while you were out of town?)