I'm guessing, but around 25 - 30 fry. If I don't upgrade my filtration this spring, I'll probably rehome two adult koi, brining my total to three lg koi. My pond is only 1700 gallons, my koi have really grown and my filters get dirty quickly, so looking to minimize my cleanings.
The year before I rehired about 60 comet and shubunkin and had the gravel removed from the bottom of my pond..it has become very dirty and my lilies had gone hay wire! I was able to place them all into a goldfish sanctuary, locally. So imagine my surprise when I returned from caring from my father, to see fry in the pond! I'd advised hubby to lift floating baskets when fish spawned, but obviously that plan did not work!!!