sick pond fish

Question
I have a beautiful fantail goldfish I am trying to overwinter in my gently heated pond in Calgary.  I have successfully overwintered fish for 5 years this way but my new fantail stays at the surface with his dorsal fin exposed to air.  He tries to go deeper into the pond but seems to just float back up. Does he need to be rescued?

Answer
Hi Mary: That is an odd behavior... I am wondering if he has a buoyancy problem.  I would, if possible, remove him from the pond and house him this winter in a tank.  I am suggesting this because it is a better environment to gauge whether or not he has a buoyancy issue.  Swim-bladder disorder, or even an intestinal blockage would keep him from being able to sink.  What do you feed your fish???? I am curious to know if he is pooping and eating???? dave