According to Behnkes' water-gardening expert Bill Watts, it's best to do this in October.

• Stop feeding the fish and don't feed them again until spring.

• Many pond owners cover their ponds with netting before the leaves fall and remove them after the leaves are all down.  Bill leaves his netting in place all winter - to keep debris from accumulating in the pond.

• Cut back plants that are in the water back, or in the case of floating water hyacinths, just lift and toss them.   You don't want them rotting and fouling up the water.  Any cold-hardy plants can stay where they are for the winter.

• Provide cover for the fish, which don't have all that foliage to hide under.  One trick is to lay a chimney pot in the water for fish to hide in.  Another is to stack bricks and lay a flat rock on top of them - that's where Bill's large koi spend the winter.

• If you leave your pump running over the winter, closely monitor it to make sure there's no ice obstruction building up.

• If you remove your pump or turn it off for the winter, then use a pond heater.  The point is to keep at least a one-foot-wide hole in the ice at all times so that gasses can escape and the fish can breathe.  Which option uses more electricity?  The heater.

Left photo by Clan UiBriain.  Right photo by Conspiracy of Happiness.