Hi James we have been keeping koi for the last 30 years may I ask what filtration you have on your pond ?
one of the lessons I'd like you to take onboard to give you many years happy koi keeping is water quality , do you have any water test kits as of yet ?
If so could you give me an idea as to the following are Ammonia, Nitrite, Nitrate, Ph do you also know if you are in a soft or hard water area ?
Another most important leason you must take onboard is koi heath , the best way to do this is read .
Weve been collectiong fish health books for many years now and have a library of over 100 books please read this following article in which I have provided Book Titles Authors names annd #those all importan ISBN numbers :-
https://www.gardenpondforum.com/articles/our-updated-library-with-reviews.11/
One of the books I'd like to bring to your attenion is the following :-