Something happened that prob dont have anything to do with the Koi since they been in there for weeks and were not new fish they were in a pen in the pond so it shouldnt have been anything to do with them.
I had a fish kill the day I posted this thread, went to the pond and saw about 20 floating bluegill. The pond is very rich right now, alge and weeds and full of fish to the point i was thinking cull some. I been allowing a neibor to feed the fish which i think he was stuffing them and I was feeding them also, not sure how much combined but i am wondering if over feeding caused it? Pond is full of alge, the fish just spawned so are prob stressed, there is a areator but maybe it wasnt enough. I been watching very closely, stopped all feeding, counted about 20 floaters yesterday picking out the ones I can get to it does not seem to be any worse. Hopefully that was it. That was the worst fish kill I ever had.