The UK forums suggest 2000 liters per fish. I believe 1000 liters are more realistic. I suppose this pond of mine is still overstock.... feeding frenzies, the more fish, the more aggresion during feeding time:

Hi
The pond does look full, but then again at feeding time the fish will al be at the same place at the same time. Your photograph does not show the rest of the pond so just from this pic I would not be able to say if you are.

What is the size of the pond?

That pond is only 18 000 liters, so if I was an hobyist, I would have been totally overstock with 80 koi in one fairly small pond.

Most of these fish are selling stock, and will soon go(hopefully ) With good filtration, lot of aeration and large daily water changes, a dealer can keep quite a lot of fish in one pond, pending sales.