To tell the truth, I'm a bit of a newbie myself, but all my fish survived
the Winter. We actually gained a couple. I put in an aquarium aerator (the
pond is about 1000 gallons) which is on all the time - Summer and Winter.
The benefits of this $15 item are many. Obviously there is always plenty of
oxygen in the water all year, but in addition, ice doesn't form around the
bubbles. And.................... the fish love swimming through the
bubbles in the early evening just after they have been fed. They do this
for about thirty minutes before they return to their foraging.

happy ponding

John