Can koi fish survive the winter in an outdoor pond? YES they can, 11 tips!

Can Gold fish and koi fish survive the winter in an outdoor pond.

In this jump in the pond blog we will answer the question can koi fish survive the winter in an outdoor pond. Koi fish are incredibly durable hardy fish. We will cover all the winter options you can take to protect your fish. 

1. Climate zone and temperature.

2. Pond Water depth

3. Do you need to use Pond Heaters?

4. Can you Take your koi fish indoors?

5. What to feed koi fish in the winter?

6. Oxygen levels in the water. 

7. Bubbler and gas exchange.

8. What to do if a pond does freeze over, yikes!

9. Do I need a A De-icer for my pond?

10. Main causes of koi fish dying in winter. 

11. Opening your koi pond in spring time

Introduction.

For those of you familiar with our blogs you know by now we give short answers and long ones. So I’ll start with the short answer to the question, can koi survive winter? Yes they can! There are many different things you must consider, how they will survive is up to you. Being armed with options and knowledge will allow you to decided what path you want to take. 

Climate zone and temperature.

Where you’re pond is located has a major impact on how koi fish survive the winter in an outdoor pond. Typically we break things down into zones with gardens. Here in Ontario we are zones 5-6. Clearly someone in zone 1 would not have to worry to much about Ice unless it’s one of those freak storms that happens every 100 years.

So winter care really applies to ponds found in zone 4-8. However, I’m going to try and boil this down to a simple approach, and avoid all the worry about zones and the fluff. We will look at it from a Temperature angle to keep one number in your mind Will help your koi fish survive the winter in a pond.

At 10 degrees Celsius (50 Fahrenheit) koi fish start to go into hibernation. I use that term loosely, they still move and will eat algae and other natural foods throughout the winter if the temperature favors activity. But a constant 10 Celsius is what you need to watch out for to help koi fish survive the winter in an outdoor pond.

What happens as the temperature drops is Their metabolism slows and they essentially stop eating and begin to live off the fat stores they built up over the warmer seasons. So 10 degrees Celsius is where winter care begins as it cools, and ends when it warms up. At 10 Celsius you treat fish differently. You stop feeding them at this temperature and begin at this temperature in the spring. 

Pond Water depth. 

If you live in a climate that experiences a deep freeze for extended times your pond’s depth Will help koi fish survive the winter in an outdoor pond. It is crucial to the survival of your koi and or goldfish. 

The short answer is  you need your pond to be about 48 inch or 120 centimeters in depth. Minimal is 36 inches or 91 centimeters.

The reason for this is that water below the ice is kept warm by the heat of the earth. In order to get that heat you need to go deeper down for it to work. If your pond depth remains a only say 1 foot or 30 cm it will freeze all the way down and the fish will die. 

If your pond is shallow or you don’t have the option of going deeper down there are a few workarounds we will cover next that Will help koi fish survive the winter in an outdoor pond.

Do you need to use Pond Heaters? 

The next option is to use a heater in the water. They do not need to be used and are only an option if you want to keep your fish active or the ice from freezing so you can see them. This will allow koi fish survive the winter in an outdoor pond in a unique way. There are some pros and cons to this. 

The pros, you get to enjoy the fish if the water surface never fully freezes over. The fish will huddle near the heater and keep warm. You have control over the environment.

The cons, Depending on the size of your pond your electricity bill will take a hit. Of all the equipment you can put in a pond, a heater will take the most electricity!

Heater failure is a worry. There are two kinds of failure, they stop working and the water freezes before you notice and you lose your fish. Or the electrical fails and shocks your fish if they are cheap. It would be prudent to buy a backup in case getting another one takes longer than water takes to freeze. And always get a good quality one to prevent electrical problems. Preventing electrical shock will help koi fish survive the winter in an outdoor pond for sure!

Maintaining a constant temperature. Heaters can cause warm and cold pockets if not set up properly. If the water gets two warm the fish may break dormancy, then if it drops, this is not healthy! Fish need to move into temperatures slowly. Sudden changes cause stress. If a heater fails and stays on warming the water up then shuts off, look out. 

So if you take the heater route, buy a good one, and buy a backup. Find a way to monitor the pond to make sure all is well and you will Will help koi fish survive the winter in an outdoor pond!

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Can you Take koi fish indoors?

Bringing them indoors will help koi fish survive the winter in an outdoor pond, well… because they wont be in one!

One method is to keep a tank in a garage where the temperature does not drop below freezing but not above 10 Celsius so they can still be dormant. It will need a small filter and bubbler. Koi fish will grow large in a decent sized pond. So a large tank will be needed, typically 200-1000 gallons. The garage option is one that can solve the space required for a tank that size. You also wont need it to be over the top. Made from durable plastics means it will last. It only needs to be effective, not pretty. 

If you move them indoors into a warm house you will need a larger filter, larger bubbler, and food as they will not hibernate. Your tank will more likely need to look better unless you have a spouse who does not care about ugly tanks!

Moving koi is not as hard as you might think. If you fill your tank with the same water from the pond and it remains close in temperature the move can be stress free. You don’t want to move fish in warmer temperatures if you don’t have to. 

When the weather cools the fish slow down making it easier to catch them because they are more lethargic. Using proper koi nets is the best option. The key to catching them is not being fast, but slow! You want to coach them into a koi bowl using a bowl net, then either lift that below out and move the fish in the bowl, or life the fish out with a koi fish sock net.

Koi Pond winter preparation that Will help koi fish survive the winter in an outdoor pond

What do you feed koi in the winter?

When the temperature begins to drop your koi and gold fish slow down. This means so does their digestion. So to prepare your fish for the winter in the fall when the temperatures drop to 20 Celsius (70 Fahrenheit) you can begin to feed your fish a fall food that Will help koi fish survive the winter in an outdoor pond. These foods are designed to break down easily in the guts. Wheat germ tends to be a main ingredient. 

If the temperatures drop suddenly and your fish slow down too mush this food will not cause them harm if it stays in their gut longer than usual. 

Koi food is one of those things, you get what you pay for. Good food breaks down well and does not cause problems it Will help koi fish survive the winter in an outdoor pond. Cheap food does not breakdown very easy. Its like glue!. In fact you can spend more on food per bag but less over all because the health of your fish and pond wont suffer and cause a further expense. So spending a little more will save lots in the long run. 

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Oxygen levels in the water. 

Once you stop feeding the fish at 10 degrees Celsius you will need to insure you feed them oxygen. There are two benefits winter brings that Will help koi fish survive the winter in an outdoor pond.

First is slower metabolism, this means they will need less air to live as they are breathing less. 

Second is, cold water holds more oxygen that warmer water does. So you have fish who need less oxygen in an oxygen rich environment, nature give you the best starting point to help koi fish survive the winter in an outdoor pond.

Debris in pond.

As the fall arrives and leaves descend they will land in your pond. You will want to clean these out the best you can as it  will help koi fish survive the winter in an outdoor pond! 

The more organic debris left in the pond the less oxygen will be available for the fish. The rotting process uses up available oxygen, co2 builds up and eventually the pond becomes toxic for fish.

The other source for organic debris that wont help koi fish survive the winter in an outdoor pond is pond plants. As they die back they will fall into the pond. A good thing to do is cut them back before they do. Cut irises back and chop the lilies near the roots. Pull any other floating plants out of the water so they don’t get caught in the ice and you can’t later. 

Plant care in the winter has some techniques as well so be sure to look out for our plant blogs to learn how to care for them.

 

Bubbler and gas exchange.

Once your pond is clean you are ready to set it up to keep gas exchange occurring as this will help koi fish survive the winter in an outdoor pond. Gas exchange is what it sounds like. You want to introduce oxygen into the water and in so doing remove carbon dioxide breathed out by fish and any debris you could not remove.

A bubbler will do all of this for you. It has a another benefit as well. Air moves a whole bunch of water, and moving water does not freeze. 

As the bubbles rise up the moving water it produces is often enough to keep your pond from freezing over. As long as there is a hole in the ice gas exchange can take place. 

Dont put the bubbler all the way down to the bottom though! You will pump cold air down there and cool of the water. All you need to do is have it a foot or 30 cm down. The water will move naturally through temperature movment to keep it good for fish. 

You will find birds love this area in the winter. They will pop in for a drink. Remember, Always have an extra air pump on the ready in case your main one breaks down. 

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What to do if a pond does freeze over, yikes!

If your pond does freeze over, want to know what will not help koi fish survive the winter in an outdoor pond? Smashing the ice! NEVER bash it with hammers, shovels, or fists like a mourning widow in desperation to open up a hole to save your beloved fish. This can kill your fish faster than a frozen pond will! The concussion effect can really cause harm. There is enough air in there to last a while, especially if your bubblers are still going! 

There are are a few options. Use boiling water and pour it in one spot until a hole opens up where the bubbles are. Another option is to drill a hole and cut out an opening with a hand saw. This however comes at a risk. You don’t want to crawl on thin ice, you being dead will not will not help koi fish survive the winter in an outdoor pond! and you dont want to put holes in your liner either so be careful with this one!

So this leads to our next option. 

A De-icer Will help koi fish survive the winter in an outdoor pond.

A de-icer is an amazing tool to have on hand. They are not always necessary, but when they are, they are awesome!

A De-icer is not a heater. They only turn on when the water drops below zero. They then stay on until the ice melts and then turn off again once it has. So they do not cost as much as heaters. 

Bonus tip. Buy a de-icer and leave it in the water near the bubbler. Do not plug it in. That way it wont turn on when unless you want it too. If the water dose freeze you can simply plug it in and let it doe its thing. Then unplug it once the hole opens up. Save on energy!

Hoop house Will help koi fish survive the winter in an outdoor pond

A more epic measure you can take for is to build a temporary structure over the pond. Often called a hoop house. It’s like a green house only smaller and less complex in construction. 

Although this seems extreme it has some really great benefits! The primary one is you can pop in anytime in the winter and hang out, although it might be chilly its beautiful and peaceful. If the water remains just above freezing the fish will still be moving but slowly. Hoop houses can get really warm during the day. So you have access to nature in the winter. 

Another benefit is it solves the problem of predators. Typically the most vulnerable your pond will be is in the spring and fall when predators are flying over head going north or south. Your fish are also slower and more exposed because surface plants are not there to hide them. All this makes them prime time lunch opportunities. A hoop house allows you to hide your fish. Not being eaten will certainly help koi fish survive the winter in an outdoor pond.

Another outcome is Tropical plants can survive. If set up to be warm enough you can keep warmer climate plants alive saving on the cost of replacing them later.  

Heater can be used to keep the water warm in combination with a hoop house.. Like a hot tub heater are set to keep the water at a specific temperature. In this case you might keep the fish out of dormancy, so you will also have to feed them. If you combine a hearer and a hoop house you are creating a warm climate you can pop in and enjoy. Making your pond a year round place to visit. 

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Main causes of koi fish dying in winter. 

Neglect can prevent koi fish surviving the winter. If you read the short answer and skipped all of everything between there and here you could accidentally neglect vital survival aspects of fish survival. Also, because the fish are under the ice days can go by where you simply look out the window to make sure there is a hole in the ice. Eventually you let your guard down and forget to look. Make it a habit to pop out and look. If you keep a close eye on your pond this will help assure koi fish survive the winter in an outdoor pond.

Faulty equipment equipment can break down, especially in the cold. Always have backups and always triple check you setups to make sure they are ready to last a winter. 

Power outage! When the power goes out, and it will eventually, don’t panic. The fish can live under the ice for a while, the larger the pond the longer they can. Follow our de-icer advice so when the power comes back on the de-icer will open the ice up for you. And if there is a long stretch of no power you can go and cut open the ice by hand. Remember don’t bash it open ever!!! If the power outage does go really long a small generator can easily run a bubbler! So having one handy could help koi fish survive the winter in an outdoor pond.

Lack of backups. Not all equipment will last a winter. And it can take time to buy a new one if it need to come by mail or its sold out. So be ready. Have an extra bubbler and de-icer ready just in case. 

opening your koi pond in spring time

A final note is spring time. Simply go on reverse through the things we spoke about. Above. Take down the hoops house. Slowly settle the fish back in the pond if you took the indoors. If you do make sure there is no more than a 5 degree difference in waste temperature. Let them slowly adjust to the change as you would when you got them from the dealer. In a bag or bowl of water that will slowly drop down to temperature.

Remember you want to feed them because you love them. If its unseasonably warm early in the year be careful, you dont want them to eat then drop back to seasonal temperatures and thet are full of food that could ferment in thier gut. Be patient and make sure temperatures are steady. Thier are not like us, they wont starve if you want a week or so for balanced temperatures. And they can also find some food in the pond while you wait. 

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