Can Koi Fish Live In A Pond In The Winter? Protect Them When It’s Freezing!

In this article, you’ll learn if Koi can live in a pond during the winter, what steps to take to protect your koi fish when it gets really cold out, and some equipment you can use.

Let’s begin!

Can Koi Fish Live In A Pond In The Winter?

Yes, Koi can live in your pond in the winter. Often called poikilotherms, Koi are cold-blooded hardy Fish. This means their body temperature depends on their surroundings. Therefore, Koi’s body temperature is always affected by its habitats.

During the wintertime, temperature changes in water trigger changes in the Koi’s bodily functions. As the pond starts to freeze, the Koi’s body’s biochemical reactions start slowing down and eventually come to a halt.

Often Koi swims and rests at the bottom of the pond as this region is slightly warmer. This movement is necessary as staying still throughout winter can cause their joints and muscles to become stiff.

However, extensively long winter periods aren’t recommended. It can affect the Koi’s immune system, weakening it and eventually causing it to shut down.

How Cold Is Too Cold For Koi Fish?

If the temperature proceeds to drop below 50⁰F, there comes a stage when Koi enters a conservative state called Torpor. At this point, their metabolic rate significantly diminishes, and the body enters a state of acute hibernation.

The Koi’s body activities and functions reduce to conserve maximum energy for only the essential processes. Thus, the animal can go without food and water for extended durations.

You must avoid feeding your Koi fish during the cooler periods. That’s because enzymes which aid in digestion are currently absent. If food gets stuck in the Koi’s gut, it can lead to severe health complications. Like a bacterial infection that may cause the stomach to rot.

3 Ways To Take Care Of Your Koi In Winter:

Set up a Winter Tank:

Unlike ordinary fishes, Koi Fish grow at a high-speed rate. Therefore, the standard tanks used for common fishes cannot be utilized for Koi Fish as they would soon outgrow them. Instead of a glass aquarium, opt for a Polyethylene tank or a stock tank. Winter tanks may vary in size, from 100 to 1000 gallons.

The filtration and heating setup depends on where you choose to set up the winter tank. For a garage arrangement, a small filter, along with a bubbler and de-icer, is needed. In contrast, a larger filter, bubbler, and koi food supply are needed for a tank set up inside your residence.

The water must be drained and replaced weekly or bi-weekly. Hence, an efficient system for draining the water is also needed. The number of water changes required depends on the warmth of the water and the rate at which feed accumulates.

Use an Indoor Koi Pond:

Although slightly expensive, building an indoor koi pond is an effective and permanent solution. These ponds can be as large as 4,000 gallons, giving your koi lots of space to swim during the winter season.

Construction of the pond’s body requires poured concrete and masonry. It should be illuminated with an internal lighting system and lined with a polyurea liner. The filtration equipment should be installed away from the pond in the utility room.

Related: Look through and get inspired with our list of 35 Koi Pond Ideas.

Leave the Koi in your Pond:

Another way to deal with long winters is to transfer the Koi into your pond. This can only be done if your pond is at least 4 feet deep. Not only is it more convenient, but this way, your Fish will require less attention.

As the temperature drops and their metabolism slows down, so will their movement. As a result, the Fish will stop eating and survive the fat accumulated during the summer and spring seasons.

Although the oxygen demands of the Koi fish decrease with reduced body function, a hole still needs to be created in the ice to ensure gas exchange. If the carbon dioxide exhaled isn’t allowed to vent out, it can accumulate within the pond. High concentrations of carbonic acid can make the pond highly toxic; this can be fatal for the Koi.

How to Protect Koi Fish In The Freezing Winter?

Here are a few ways to keep your koi fish protected and healthy during the cooler season:

Pond Depth – How Deep Should a Koi Pond be for Winter?

The minimum depth of the pond where the Koi are being kept should be at least 4 feet deep. This ensures that the entire pond doesn’t freeze over, leaving room for the Fish to move around. Moreover, increased depth protects them against predators.

Clean The Pond:

Keep your pond clean. Before the water reaches 15⁰C, be sure you’ve cleared out all the dirt, fallen leaves, and waste from the pond. The accumulation of contaminants can reduce oxygen levels, while the ammonia and nitrate levels increase as the organic matter deteriorates and affects the water quality.

Use Pond Treatments:

The key to avoiding infections and the spread of bacteria is applying anti-parasitic treatments to the pond. Unfortunately, the slowed metabolism during winters makes recovery all the more difficult for your Koi fish.

An effective way to maintain the pond is the use of cold-water beneficial bacteria. These organisms tend to thrive at temperatures lower than 50 degrees. These bacteria degrade ammonia, nitrate, and waste in the pond, keeping the water healthy, clear, and clean.

Keep a Hole in the Ice:

The creation of a hole is necessary to provide ventilation within the pond. A pond aerator produces rising bubbles and water currents, ensuring the water doesn’t freeze entirely. In addition, it promotes the circulation of gases and helps manage oxygen levels.

De-icers and heaters are also effective in the maintenance of pond water. A proper heating system comprises a boiler, heat exchanger, and temperature probe. It keeps the water temperatures above 12 degrees.

The de-icer keeps the hole open in the pond as it floats around. Thus, it allows the harmful gasses to escape, which would otherwise build up, causing your Fish to suffocate to death.

Further Reading: Should You Aerate Your Pond In The Winter? What You Need To Know!

Keep The Pond Warm – What temperature can Koi Fish live in?

Koi fishes are hardcore in nature. They are resistant and can survive severe conditions; for example, they can live through brutal winters by hibernating under the ice. However, these fishes thrive at temperatures between 65 and 75 degrees.

Use a Cover

For increased protection from harsh winter storms and predators, your pond can also be covered. Several koi pond covers are available in the market, ranging from solid, net, porous, and even ice covers. Each has its advantage and unique properties.

How To Prepare Koi Fish For Winter

Reasons Your Pond Will Freeze Over:

The most common reasons that may cause your pond may freeze over include:

  • Cold Weather
  • Power Outrages
  • Lack of care and attention
  • Incorrectly installed equipment
  • Low quality or damaged equipment
  • Lack of maintenance

Frequently Asked Questions:

Can Koi Fish Survive Winter in an Outdoor Pond?

Yes, if all the essential requirements are kept in mind, there is no doubt that your Koi fish can survive and thrive in winters. However, consistent pond maintenance, proper heating arrangements, and preparing beforehand is key to protecting your Fish during the cooler seasons.

Can Koi Fish Freeze and Come Back to life?

Many wild types of Koi Fish can live through harsh winter conditions, provided the water has sufficient. However, since they can’t breathe through the surface, the oxygen-depleted water can prove to be fatal for your Fish.

Jack Dempsey