Hi all folks Robo here: new to this group .I have more then several Koi and several ponds.In the past years we would leave all large pond fish in the mud pond it is 100'x100' and depest about 6 feet. The water goes down to about 4ft of water and freezes top side about 4-6'' the Koi go deep into the mudd and "metab-out " we have lost several good pets over the years due to "winter stress" I am looking for Ideas for winter housing requirements ----- less stress for the two. One is 20- 26"the other smaller .I build Ferro cement ponds and have lots of space to place housing for them ... These guys and gals have been in the mud pond for years and are use to the large space Thanks Robo