my fish! is sick!

Question
my fish is a koi fish. and i have four of them but one of them is sick! he keeps swimming on his side and floating down and around almost upsidedown. I'm not sure what to do, how do i make him better?!!!

Answer
Hi Amanda,
 It is pretty difficult for me to say what is wrong with him from here.
What kind of tank or pond are the fish in?  How large are they and have you had them very long?

-- Ron
  rcoleman@cichlidresearch.com
  Cichlid Research Home Page <http://cichlidresearch.com>