Question
Hi one of my pond gold fish has large white spots on it side.  He has about 4 but otherwise seems well.  Any idea what it could be.  I have 10 other fish in there with him who have none.  It is an etablished pond we have with some fish as old as 15 years I believe (inherited from previous home owner)

Answer
Hi Louise,
It sounds to me like your fish as Ich.  You can go to a petstore and buy liquid treatments for Ich.  Eventually, your other fish will become infected if this is not treated now.  The results could be the death of all your fish if not treated.  This is a parasitic disease, Ichthyophthirius and when the parasite matures it will drop off of the fish and fall to the floor of the pond and release many larvae.  Here is a brief explanation of the disease http://www.fishdoc.co.uk/disease/whitespot.htm

Most large petstores carry several types of ich treatments.  Just ask the proprietor.  When I had this problem with aquarium fish, I went to a store that specialized in tropical fish, but the disease is also common amongst pond fish and marine fish.  I hope this helps.
Tom