Went today for my boss and there was this poor little male crown tail his water was yellow

and full of poop he was barely breathing.

I stopped a worker and said, "Would it be ok if I changed his water because if not he is going to die. The worker said,"Oh how awful poor little guy. The person that works in this department should take care of these fish better." To which I said,"Yes they should but they never do." Then he said go ahead and change it no one is looking. So I did. Luckly the water that came from the spout was the same temp he was in and they had water conditioner and stuff right there. Even had a measureing cup that I put him in so I could dump the dirty, nasty water out of his cup.

I would have brought him home with me but my wallet was here at the office and I had no money with me. His body was curved I am not sure if that is from the nasty water or if it is an illness. If I go back and get him can I fix him with meds and clean water? I stood there a few minutes after I switched his water and he definatly perked up a little he was no longer laying completly sideways and was moveing a little.
Edit: Wanted to add he also has very bad fin rot hardly any finnage left.