You never mentioned what part of theworld or states your from. It may
be all together possible your fishw ill do justfine outside in the
winter if your not in an area where its liable to freeze the entire 2
feet deep. If all yo get is weather that only freezes your pond to
10-12 inches deep, they will do just fine, They will probably do just
fine in thepond if the water freezes to 16 inches deep as well. Just
keep a hole open in the ice to allow gas exchange, do not feed and
wait until water warms up to 50+ degrees for at least 10 days in a row
before feeding them. It also helps to make sure there is no junk and
detrius and crap on the pond bottom so cleaning it out is a must. I
have seen goldies and koi stay in as little water as 4" deep with
24+ inches of ice on top of them and do just fine.