Are we looking at the same problem 'smiling bob' is addressing ?

we need bth length and size too when come to koi ?
There is a 25 years, small pond in San-Mateo, northern California. No more than 2' deep, total way less than 1200g (forgot the number the builder told me). There were 6 huge koi in the pond, the largest few were more than 40" long, much bigger than the 36" GC of 2006 bay-area koi show. has a small sand filter that got clean once every few years. the pond was almost completely covered by water hynacinth (spelling?). the koi were placed in the pond shortly after completion. I was given a tour of the pond 4 years ago. I was impressed with what the owner achieved over the years. Not a single thing about the pond meet the slightest requirement of 'high end' hoi hobby requirement, yet koi grew to be monsters.
stan