I have koi & trout (among other fish) in my pond and don't seem to have a problem with it. I've had more problems with the bluegill in my pond but I think that was from too many mature bluegill and not enough spawning area and it stressed them. The koi and trout both seem happy, grow well, and feed together during feeding time.
Would be nice to see some photos of this. What are your seasonal water temps? And I have seen bg happily coexist with both trout and koi. Especially trout. Even gsf. We have a winery that has a trout/bg pond they hand feed all season long and then lets kids fish for the trout in the Spring. I think it is called Indian Rock. Usually the biggest is around 10 lbs, but this year it was only 9. There are no koi in there, and never will be. But plenty of trout and bg. Too many mature bluegill and not enough spawning areas so they got stressed? You have many firsts my freind, never heard of anything like that either.
