Slick I've put a list of the koi koi health and fish disease books we own in our library as an article only recently it includes the title ISBN numbers of books when they have them and Authors names .
When we first started out ( this is our 28 year now) I adnit I lost fish habd over fist because I didnt really understand the ins and outs of fish keeping , then Val bought me my first book The Salamander Manual of fish health (now interpet) and the rest is history .
Our hobby turned into a sort of self perpetuating one due to sales of koi grown on by us buying equipment food small koi or koi/fish health books we now have a large library we can call on to clarify this point or that t the last count it runs to 95 books/manuals/pamphlets .
In 28 years weve lost only 8 koi our last death being from old age last summer of our second 27 year old koi tiny, I think this may well be the way forwards for you .
When you say BKS I take it you mean the BKKS yes , could you please tell me what section/club are you in please as I may well be able to tell you which HSC official is in your area , our own section the Plymouth one has the former Chair of the HSC as a member who we are friends with.
The remit of these HSC officials "call them health officers" is to visit your pond to give advice on treating your sick koi .
Have you ever thought about buying a Microscope and taking scrapes to look for parasites , when you have read a few books buy one they come in most important , there is a thread about microscopes on this site .
Dave