It is a common myth that you can’t leave your pond fish outside once the cold sets in. Actually, fish do just fine during winter. That said, Deck and Patio’s Outdoor Living Expert, Bill Renter, does caution to be alert. When ice covers the pond, the fish might not be getting enough oxygen.
This can be remedied as long as you give them:
- two feet of water to swim in,
- oxygenate the water,
- and keep a hole in the ice with a heater, bubbler and an aerator. This allows the naturally produced gasses to escape from under the ice.
If the above efforts fail to keep it from freezing, Aquascapes Inc. designs manager, Gary Gronwick suggests using a pond de-icer. “This will keep a little hole in the ice so gases can escape,” he says. “While some recommend boiling water to create an opening in frozen-over ponds, that should be discouraged. It will only ice up again quickly.“
Gronwick also says to avoid chopping or sawing the ice to open a hole. The noise and vibrations will stress out the hibernating fish to a point they could die.
That done, Mother Nature will do the rest. The fish will spend the entire winter hibernating at the bottom of the pond, or in a cave designed for this, and then will slowly wake up as the water warms in the spring. The fish do not need to eat during this time and, in fact, shouldn’t be fed at all.
Before winter sets in, carefully look over your plant material and remove dying plant material. These materials rot and build up poisonous gases that can’t escape through ice when it forms. Such conditions might mean the koi are no longer simply hibernating, but are in a dangerous state of torpor.
Hardy water lilies (shown here) that float on the water’s surface and have a short blooming period can withstand the cold winter months nicely. Lotuses also can withstand the cold winter months because they bloom in summer and go dormant in winter. Note that frost kills water hyacinths; water lettuce, which fights algae, should be wintered in a warm spot that is well lighted as they will not survive in the pond over winter.
[…] our clients ask our experts if they should close down their ponds or fountains for the winter, our answer is frequently, No! Most ponds — even stocked with koi — can operate during […]