fishes disease

Question
fish breathing rapidly and not swimmingit is tropical fish

Answer
Hi Sam
I'm afraid I'll need a bit more information to try to help out.  It could be a parasite problem, it could be a gill disease problem, or it could just be related to the water quality.  

Do you know what you're ammonia, nitrites, and nitrates are reading?  
What size is the tank?
How many fish and what kind of fish are in it?
How often do you do water changes?
How new is the tank?
Was the fish showing any other symptoms, like gasping at the surface, rubbing on objects in the tank, darting around the tank?
And he's not swimming, is it lying on the bottom?  If so, when you tap on the tank or put the net in to net him out, does he swim away normally or just lay there?

If you can get back to me with those answers, that would help out a lot.

Christy