build a fish pond

Winter Pond Care

Winter Pond

Life in a winter pond could be potentiality deadly for your Koi, Pond Fish and plants. You should start your winter care before the winter months come into season, this will be important so that your plants, the fish and the pond itself make it through the winter with out problems or damages.

In the fall is when you should start your winter care. Plants, fish, pumps, UV lights and more require attention before temperatures drop. Hardy pond plants will survive, but tropical plants need to be wintered over, they need to go dormant, but they can't freeze. Store tropicals in a place where the temperature stays about 40 degrees, such as an unheated garage.

When leaving hardy marginal plants in ponds, make sure they sit just below the ice line and do not sink to the pond bottom where they can drown. Hardy lilies can remain in the water, but only in the deepest part of the pond.

How your Koi get prepared for the winter season.

The carp has a communication system from sensors in the head and the eyes that transmit light intensity directly to an area of the brain that triggers changes in the body. These changes are of a hormonal nature and as one level raises, another declines. In addition to this, many hormones appearing begin to create a biochemical domino effect as presence of one hormone trips another that trips another. The result is, the fish experiences two things as a total organism; One, it begins to redirect energy to other uses compared to what it previously directed energy to. Two, the body is being set up for the winter season. So in this time of year, energy is diverted to storage, less to growth and new cells are being created for future breeding in females.

Fish are cold-blooded creatures, or poikilotherms. They don’t produce their own heat and so they have developed enzyme systems to provide them with bodily functions such as the production of energy, regardless of temperature.

Fish survive winter because they are capable of producing enzymes that function in cold water. These enzymes are called isoenzymes. They are produced as needed and they work in colder conditions. As the water gradually warms up, these coldwater isoenzymes are no longer produced, and the regular enzyme systems begin to function to support the fish.

Your Koi will show a more aggressive feeding style before the winter season approaches. You will also notice your Koi occupying different areas and levels in the pond as water temperature and light change.

Koi are cold-blooded animals that should not be fed when the temperature falls below 55° F and stays there for ten to fourteen days and night. Their need for food is greatly reduced and correspondingly, so is the rate of digestion. If fed after this point the food will not have time to digest so it will stay in the Koi's body, rotting all winter long.

You will shut down your pond when you stop feeding your Koi. And when do you stop feeding your Koi? At 55° F for 10 consecutive days!

Before the Spring Seasion Arrives

Before the fish get “warm” in summer, there’s a narrow period of time where the water temperatures are too cold for the fish's immune system to function optimally, but parasitic and bacterial populations are proliferating at explosive rates, this is known as "Aeromonas Alley” and it happens between 42° F and 62° F. During this period of time the fish are prone to develop illnesses from these parasites or bacteria. It is important to protect your Koi during this time. One of the ways of doing this is to not feed your Koi and to give them something to help boost their immune systems.

Sabbactisun keeps opportunistic invaders off your fish until they can fend for themselves. If your fish already show signs of open sores (ulcers), it’s best to heat the water slowly to 70° F, to allow the fish’s immune system to kick in.

KoiZyme is a Great New Product to help combat Aeromonas, Pseudomonas and other Pathogenic Bacteria.

DO NOT FEED your Koi until the Water temperature (not the air temperature) reaches 55° F and stays at that temperature for 10 days and nights.

Medicated food is HIGHLY recommended along with Pond Salt in the Spring.

Koi and Pond Fish Care for the Winter Months

The pond is more balanced during the winter then the summer months, your pond is not struggling to cope with the abundance of artificial food and a large population of feeding fish.

If you built your pond properly it will be deep enough to support your fish through the winter.

They will go into hibernation. They will fold their fins in close to there body, they won't move but their senses will still be working. As the temperature of the winter pond drops the fish will move closer together where their bodies will be touching. Your fish will not eat during the winter months, do not try and feed them either.

The cold water naturally holds lots of dissolved oxygen. Since the fish are not eating there's no waste for the micro-organisms to break down. You don't want the ice to cover the whole surface of your pond. The carbon dioxide needs a way to escape out of the water. So never let your Pond freeze over.

Put expandable floatation devices in place on the surface to absorb the impact of expansion as the surface freezes. A beach ball will be perfect for this. You can also place an aerator within six inches from the surface of your pond water. The aerator will keep an opening if ice develops. You want the aerator at the top of the pond not the bottom. If at the bottom it will circulate the cold water around your Koi causing their body temperatures to drop and you don't want that.

Koi can withstand temperatures down to 33° F for brief periods, but will be stressed. They will do much better at 39° F. If the water remains cold for any duration, the fish may be noted lying on their sides as a sign of the extreme stress. A deeper pond will always have less potential for winter fatality.

Remember, your fish are in a state of hibernation, you do not want to smash the ice or it will cause your fish to go into shock. The best methods for the winter pond are to use a pond heather to keep a hole open, or pour steaming hot water on a section of the ice to melt it away.

Remember, your winter pond will always be full of life even when it looks as if everything has expired. The life is under the water and it is vital for your pond to keep it that way.

Heating Tip: Use several small pond deicers in place of one large (expensive) one. Plug them into two different circuits, in case one becomes overloaded. Always use GFCIs when electricity is used in or near water.

Plant Care for the Winter Pond

You can start your winter planting a few months before winter. You can plant winter hawthorns in the water garden so that they will become established over the winter months and will bloom in the early spring months.

If you have any tropical plants in your pond you will need to remove these for the winter. If you have sturdy or hardy plants they should be fine, just keep an eye on the temperature of your water.

If you have container plants in or around your pond, you need to think about the containers your plants are in. Are they able to withstand freezing temperatures with out the possibility of breaking? If the containers are made out of ceramic or glass type material, you might need to bring them indoors so they won't break, split, or crack

Stop fertilizing submerged plants about 3 weeks before the average frost date. In warm climates where frost is not a concern, stop fertilizing when the pond temperature falls below 60° F.

Submerged plants that are hardy in the area may be left in the pond. More tender plants should be brought indoors.

Reduced sunlight also means that plants stop growing and photosynthesizing, with plants dropping their leaves and dying back.


A mature biofilter is one of your ponds greatest assets. It is essential for maintaining a good, stable pond environment. During the winter your fish and plants will not need the biofilter to sustain them.

You want to keep the beneficial filter bacteria alive so it can do its job during the summer months. It is best to keep water running throughout it but, there is a risk to your winter pond in doing so.

It can chill the water, which in turn makes the whole pond cooler, and that is risky for the health of your fish. A useful compromise is to put a reduced flow of water through the filter as well as insulate it so that the water doesn't get chilled. But at all cost keep your filter alive.

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Pond Deicer

Pond Deicer

A floating de-icer can be extremely helpful to keep an opening for gas exchange.

  • Pond Deicers maintain a hole in the surface ice to allow gas exchange between the water and air.
  • 1250 watts
  • For ponds up to 600 gallons. Any pond over 600 gallons would need 2 units.
  • 10 foot power cord.
  • Thermostatically controlled
  • 7 inches in diameter by 3 inches tall
  • 3 Year warranty.

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