Your always going to have problems with any intensively farmed fish this is why many of the employees have qualifications in Aquaculture with some of them becoming experts in their fields , however intensive fish farming and a small private pond are two totally differing things .
Val and I dont claim to be experts I dont think anyone on this site does but we have years of fishkeeping behind us and a strong knowledge base because we chose to buy books on our hobby as well as books on fish health and educate ourselves .
The problem with many fish keepers is they think that fish are throwaway comodities that dont live very long when infact they do totally oposite and can in some cases outlive their owners if they are correctly looked after .
But Lee has a problem of his own making in that he didnt QT his new koi (a fatal mistake for many of them) but our job is to educate people as best we can and I think Lee if he stays o this site will remember his mistake and how we as a forum went about helping him and go on to educate and help others himself .
At the moment we cant say anymore until Lee gets the scrape on his koi done and comes up with the parasite that is causing so many koi deaths , we do have a strong idea as to what it is but wont say anything unless its confirmed as the parasite we are thinking of because if we were wrong it may do his koi more harm than good .
Dave