There are so many variables when it comes to stocking. I have seen it all from suppliers with excessive ratio to 1 fish in 500 gallons. I have other pond friends and I have talked to them to get thier take on it. Some are breeders and suppliers though, I guess thier input should be taken as such. It all depends on how much circulation, filtration and o2 you have supplied to the fish.
I was tryin to help someone a couple days ago and I feel thast I got a little slap in the face and they walked away which is fine, I only tried to help with my info. I will not offer any suggestion or assistance in pond building anymore, but here are some links below, please use them.
I am running 1" per 16 gallons right now. My Goldfish are at thier maximum, near 12" overall some of them. Of course you only need to measure thier actual body mass. So they are around 6" body mass. My Koi are running about 12" body mass. I have a total figure of 175" of fish. I am alloted 190" max and 160" suggested for my pond.
I bult a 30 gallon vegi filter yesterday to help consume more more nitrate and waste. I designed it with a vortex effect. i was amazed at how much waste accumulated in the bottom center of the filter within 1 hour. So anyhow that is this years test filter. I'll make a vid of it later. I dont know why my type style is changed, i guess I hit the worng keys when typing with my big fingers, sorry LOL..
So anyhow check out this basic calculator if you have intentions of building a pond in the near future. http://www.hongslandscape.com/pond_calculator.php
Also listen to this Vetrinarian on Ponds. This guy is a guru. http://www.youtube.com/user/nightopz