Fish in the Winter

Are there any fish that can survive winter in a water garden? How deep would the pond have to be?

—Annamaria Tegarini, West Hartford, Connecticut

Melinda: Koi and most other water garden fish can survive in ponds as long as the water doesn't freeze solid. Check with fish suppliers for specifics. You can use a pump to circulate the water and prevent freezing, or include a deeper area in the pond—at least 2-1/2 to 3 feet deep—that's less likely to freeze solid. You will want to make sure there are some breaks in the ice to allow toxic gases to escape the water while allowing oxygen in. Reeds and other plants poking through the ice will do this, or create your own airways by using hot water to melt holes through the pond's surface.