hi all, this spring we finally completed getting the pond in the backyard of our new house. It's about 6500 gals and we have only a handful of fish (koi and some comet "feeder fish" that we use to ensure the water and our efforts were working before introducing the koi)

Heres my concern: We had a tiny pond at our previous house and brought a few of the koi with us. We kept them in a 100 gal aquarium till we were able to get the big pond in ground. One factor we did not account for was all the work the new house needed (buying an old house is always a gamble, hu? and this was serious stuff, foundations and roofs and falling ceilings) and we were pressed into keeping the fish in the aquarium for 2 years while the house repairs were being made (no worries, they are completely healthy and happy).

I have heard the old adage about fish growing to suit their environment, but have I stunted these few fish since they are now 4 years old and only about 9 inches long ? They are otherwise healthy and active and normal koi. can they recover now that they are in a considerably larger pond ?

I heard that there is a hormone released by the fish and due to pond size/concentrations of the hormone, the fish can be stunted, but if the pond is larger and the concentration diffuse can they pick up and continue to grow "normally" ? is this the real reason for fish growth (it appeases my scientific side) ? We are changing pond water in hopes of greater diffusion of this hormone. Finally, its been only 3 weeks since moving all the fish and there is no way we could see real growth yet, so any of your educated thoughts are welcome.