I recently put in a new pond and i don't know why but over the last 2-3 weeks there are dead fish in the pond every other day. I have a pump and filter (which prob should be bigger - but I'm trying to get a bigger one) and there are also some pond plants (lilys etc).
The fish appear to be shedding their scales (it looks like peeling sunburn) and then a day or two later they are dead. i have checked the Ph level and it is about 7.5 - 8.
I had transferred one fish fom my old pond but he too has now died.
Take one of the dead fish and a sample of the water to a garden pond expert, phone around the garden centres to find one. Also check this site out, lots of info on fish problems and illnesses. Good luck http://www.fishdoc.co.uk/disease/diseasehome.h tm