Caring and Feeding Fish Throughout the Winter

     In most parts of the United States it’s best to leave fish in the pond during the winter, providing the depth of the pond is adequate (18˝ or deeper) and there is little or no water circulation. The denser, warmer water will sink to the bottom of the pond, where it will be insulated by the cooler surface water or ice, and fish will gather in this deep, warm area.   Some types of fish, such as fancy goldfish with ornate tails, bubble eyes and lionheads, are sensitive to cold weather and should be brought indoors.

     As winter approaches, pondkeepers should monitor pond water temperatures daily. When the water temperature falls below 39°F (many koi keepers stop feeding koi when water temperatures fall below 50°F), pondkeepers should stop feeding the fish altogether.  You may worry about not feeding your fish, but you can be assured  that your fish will naturally rely on stored energy reserves to sustain them throughout the winter months.

Taking these few steps now will ensure your fish will survive the winter and enjoy a successful pond season next year.

Fall Feeding – Planning Ahead

In most parts of North America, water temperatures start to dip in early fall (September/October). Make sure you have a thermometer so you can monitor the water temperature as the fall weather progresses. It is time to start prepareing your fish for the cold months ahead.  Change fish diet to accommodate the changes these cold-blooded creatures will undergo. Wheat-germ-based food is ideal to transition fish in (and out) of winter because it is highly digestible at low temperatures. This is especially important because in the colder months, fishes’ metabolism and the pond’s ammonia-reducing biological activity are greatly diminished.

Fall/Winter Pond Checklist

To ensure you cover all of the necessary fall pond prep steps, keep this checklist handy:

  • Reduce the number of leaves falling into the pond with netting or remove them with a pond net
  • Clean out the pond as outlined above
  • Cut back dead or dying aquatic plant foliage during the fall
  • Purchase a wheat-germ-based pond food developed especially for a spring and fall Diet
  • Disconnect the pump, filter and UV clarifier before water freezes
  • Store UV clarifier indoors for protection
  • Store filters indoors (if manufacturer’s directions suggest)
  • Purchase or have the pond de-icer ready for installation ( in risk of ponds freezing over). It will melt a small opening in the surface, allowing noxious gasses to escape.  You can leave it in your pond unplugged, then plug it in when needed.

With the onset of spring weather now is the time to get outside and begin to prepare your water garden for another successful season. Your pond has been dormant all winter and needs a little care to make it beautiful again. The following steps may be helpful to you in getting your water garden into shape.

Winter Pond Equipment

     It is important to have a de-icer product.  Investe in a de-icer;  waiting until your pond freezes over may be too late. 
Gases, which are produced by decomposing organic material, are toxic to fish when they are trapped beneath ice covering the pond’s surface. De-icer’s are designed to keep an area of the pond ice-free during the winter, allowing harmful gases to escape through the opening. In small ponds, a de-icer is especially helpful in preventing ponds from freezing solid. For fish safety, it is extremely important to never break ice on the pond because the shock waves can be detrimental, and sometimes fatal, to fish.

    There are energy conserving de-icers designed specifically for ponds that are inexpensive to run. We have an assortment of de-icers in stock. 
If your pond freezes and you don't have an de-icer, as an alternative, you can  melt a hole daily by setting a heated pan of warm water on the surface.
     Either method of creating an ice-free opening will let pond inhabitants breathe, maintaining their health and longevity.

 Remember, winter can be stressful on a fish’s immune system. De-icer’s alleviate stress during the winter, making it easier for them to withstand diseases that are more prevalent in the spring.

1. Walk around and inspect your pond, make any repairs as needed.

2. Remove dead leaves and debris that have accumulated in the bottom of the pond. A 15% to 25% water change over a few days to eliminate the dissolved organics built up over winter is beneficial.

3. Startup water changes per above (or any water changes), need to be treated with a water conditioner such as Stress Coat to remove harmful chlorine or chloramines from the tap water.

4. Clean out and start up the filtration system. Beneficial bacteria can be added to keep the pond naturally balanced.

5. Ammonia and nitrite are the major causes of fish loss in ponds. Pond test kits offer a quick and accurate way to evaluate pond water quality and stop problems before they occur.

6. Check fish for infections, torn fins, ulcers and open wounds that may develop after a rough winter. 

​7. Your fish may start looking for food as the temperatures warm up. Feed with a low protein, high-carbohydrate, vitamin-enriched diet when water temperatures are about 45° F to 70° F.

   Pond salt is also beneficial to provide your fish with essential electrolytes.    Pond water can be tested with a salt level test kit.

8. Pond plants should be divided and repotted. Plant food tablets should be added to pots to provide the essential nutrients. Liquid food or tablets can be added when floating plants such as water hyacinths and water lettuce are added to the pond.

 A build-up of sludge and dissolved organics reduces the oxygen level and creates a breeding ground for disease-causing bacteria. Keep your water clean and clear!

Prepping the Pond

Fall is the time to clean out your pond (before water temperatures fall below 50°F). This is recommended since the fish will still be active and less likely to sustain injuries during cleaning.

     As air temperatures begin to drop, so do water temperatures. During this temperature change, the needs of pond fish are altering as well. It is very important to protect the fish from their changing surroundings including falling debris and decaying leaves.

     Scoop up fall leaves from the surface with a fine net. You may want to pump some of the water out of the pond to expose the planting shelves around the pond periphery. This will make it easier to hand remove leaves that have adhered themselves to the pond edges and shelves. Using a hose nozzle, blast off the accumulated debris and sludge around the pond shelves and edges, and then remove remaining debris with a net or pond vacuum. When replacing the water after cleaning, remember to add a water conditioner to remove harmful contaminants like chlorine, chloramines and heavy metals.

     Once the pond is clean, this is a good time to add a pond net if there are trees nearby to protect it from falling and blowing debris.  Securely fasten the net around the edges to prevent leaves from finding their way underneath it. However, if you have frog inhabitants, it is helpful to leave a small opening or two to provide them access to and from the pond. Avoid letting the net sag into the water. Not only will it create a hazard for your fish, but leaves will collect in the submersed area and decay.

Spring Start-up Steps for Ponds

Close up the pond for the winter

    The first step is to determine when you should shut down your pond equipment: the pump, filter and UV clarifier. If your winter temperatures are moderate, you may continue to run pumps to keep the pond surface from freezing. Where temperatures are more extreme, it is recommended to shut the pond down for two reasons. First, the pump will mix colder surface water with the slightly warmer, more stable temperatures in the pond bottom where fish take comfort and hibernate. Second, you risk the chance of diverting water out of the pond and emptying it when the flowing water begins to form ice, especially on features like waterfalls or streams. ( We shut down our waterfall features and uv lights, but leave our filter running)

    Store your equipment indoors safe from the elements. It’s also a good idea to clean and inspect the equipment and replace any broken components. When shutting down the pumps, filters or any other equipment if you are storing the equipment outside or in an unheated space make sure that there is no water left in the device that may ice up and cause the body/housing to break. If kept inside it helps to place the pump, if it is submersible, in a bucket of water to keep the moving parts and seals wet.

Don’t forget the plants…

    Plant life can also be a source of debris. As marginal and deep-water aquatic plants begin to die back, prune dead stems and leaves to prevent decay in the water during the winter.

    In late fall, recommend removing non-hardy aquatic plants like Water Hyacinths or tropical lilies from the water. You can store your plants in warm, frost-free conditions, like indoors, until next year.

    For marginal plants in baskets around the perimeter of the pond, move them to deeper water to prevent them from freezing in pond ice. Hardy water lilies can be left in deep end of the pond over the winter. Bog plants can be insulated with straw or a commercial insulating material.