I can make something to go over the pond. I understand that you mentioned too many fish for the size of pond, these are very small koi at this time, as they grow, I have another pond that I will be putting some of them in, but I want to make that pond much larger over the winter time. I am trying to think ahead, for when they grow, for when it gets cold, and prepare. I do know they will outgrow the area they are in, so it is not a permanent home. A coworker has a pond and said he just runs his pump all winter long, never ices over, and his fish (1 fish) does fine. I just wanted to take the best route for keeping the fish safe over the cold months, and consulting what others in my area(zone) might do or suggest to do.
May I ask, if I went the route of the landscape fabric(which I have a lot of), how will that work for protection of freeze? Don't mean to ask a dumb question. I also had seen some plastic thick bubble wrapped material at lowes, that you put over pools and outdoor jacuzzi tubs for the winter. Why could that not be used, if a place cut in it for air ?