White Spots on Fish

Question
We have 28 fish in our pond which is pretty big and all seem fit and healthy except one I noticed this morning. He was hanging about at the surface and I thought he was dead and went to net him out when I realised he was still alive but not well.   He has a couple of white spots on his fins and his body looks slightly cloudy too.
I took him out of the main pond and put him alone in our smaller lily pond and wonder how I can treat him.
Thank you for any help or advice you can offer.
Kind regards
Wendy

Answer
Hi Wendy,
How big are both of the ponds in gallons or liters? And also, What do the spots look like?
It is most likely of a disease so as much info I can get (water quality, pond size, type of fish, size of fish, water stats, etc.) will help me help you.
Will