Wintering over our koi in the garage....


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I am planning to bring my Koi into the garage to winter over. I believe we have lost them in recent years due to insufficient aeration; last year we had a thaw in January and the fish could not go back into dormancy. At present our outdoor temperatures are ranging between the upper 30s and 60s and I already see that our fish are eating much less.

We are planning a large tank with a water filter, insulation and aeration. Our garage is also insulated and shares one wall with the house. However, it has no heat source and in February the temperature can go to 20° below zero outside.

Should the fish be kept in darkness? Is it all right if we do not heat the water? ! Any and all ’words to the wise’ gratefully appreciated. Thank you!
 
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I'm going to start with saying I think your conclusions about why you lost fish over winter may be off base. Aeration is not really the issue - it's more likely keeping an opening in the ice to allow for gas exchange. Koi don't have trouble "going back into dormancy" - they are cold water fish and have no trouble adapting to cold temperatures. If the water warms up temporarily mid-winter they may get more active for a time, but they will react appropriately to their environment. And not eating when the water temperature goes down is not an issue at all - that's an expected response. Also remember your fish don't care what the air temperature is - they are only concerned about water temperature. If your pond is deep enough, those 20 below days feel just like 20 above days to them.

You can of course choose to bring your fish indoors - others have done it. But that can cause problems, too - stress on the fish from being caught and moved, changes in water temperature/parameters, and water quality being difficult to control in a too-small tank are a few that come to mind. And year after year your fish will get bigger and bigger making those issues exponentially larger factors to deal with.

How big is your pond? How deep? How many fish? How big and how long have they been in your pond?
 
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I know of several people who bring their koi inside their garages for winter. Most of them use an Intex pool and those are very reasonably priced right now. The filtration on those pools is useless for koi and most everything else, so some other filtration must be used. If you can transfer the same filter system that you have now to the pool, that would be ideal. That would prevent your new pool from having to go through the nitrogen cycle again and would probably keep your beneficial bacteria alive through the winter. If the water doesn't get too cold, that is.

I doubt you would need extra heat, but a simple shop light or two with full spectrum bulbs that was hung over the pool would help with lighting. And you would probably need to put a net on the pool to keep the fish from jumping out.

My better half and I have just moved a 10' Intex pool into a lightly heated room in the barn. It houses goldfish fry and water lilies. The fish and lilies would have been fine outside, but the pool wouldn't survive our winters. They wouldn't hold up to water freezing in them, so if your garage gets that cold, that could be a problem.

There are several threads about this on koiphen.com if you would like more information.
 
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When water is cold, it holds more O2, but fish will still require fresh O2 and a way to "off case" the CO2 they exhale. Keeping a hole open is how CO2 ( carbon dioxide ) will vent out.

You look like you're in a cold climate....how deep is your outdoor pond?
 
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Hello Pond Forum allies,
Thank you for your thoughtful and considered replies.
Our pond outdoors is 3 1/2 feet deep at least and holds around 9000 gallons of water. We have always maintained a hole in the ice over winter and nevertheless have lost fish. There are two rock shelters where there might be less circulation over winter and I thought that perhaps they created dead zones. The pond is so large and the fish grew so large that I thought perhaps a single hole in the ice was not sufficient to create the oxygen exchange needed for our largest fish. The smaller ones made it through the winter.
This summer the fish were so active, ate enthusiastically and appeared so happy during the months of June, July, August and most of September. I read somewhere that when the water goes below 50° a Koi’s immune system will be challenged. Is this true?
They have mostly stopped eating now – October —And I do not believe that they will begin to eat again most likely until April or May. Can this be?!
Again, all insights appreciated!
Evelyn
 
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Your pond is certainly large enough and deep enough for your fish to overwinter outdoors. And honestly, housing 25 good sized koi indoors all winter is going to be a HUGE undertaking. Catching them will be the first challenge, but you will risk losing them all if you cannot maintain the water quality over the long winter. Do you have the ability to do water changes on a regular basis? How big of an indoor holding tank do you imagine you'll need?

Here's a question for you - are you able to keep your pond running all winter? That's one way to keep the water quality high and keep the off-gassing efficient without worrying about keeping a hole in the ice. I know that our pond is frequently buried under many inches of snow - hole or not, it's still completely buried. But because our pump runs all winter our water keeps circulating and the fish stay healthy. Just a thought... If you can't keep the whole pond operating, maybe you can figure out a way to keep some water movement going - drop a pump in and create a temporary waterfall for winter. Just don't put the pump all the way to the bottom - you want that warmer water at the bottom to be undisturbed for your fish as they will naturally seek the warmest spot for winter.

Koi do stop eating when the weather gets cool and yes, they may not eat again until April or even May... but that's how they are built. Imagine a bear going into hibernation - months without eating and yet they survive year after year. When we had koi, they came out of winter bigger than they were when we last saw them in November or December. If you can see you fish during the cold months, you will notice that they do continue to do a bit of grazing in the pond, slowly moving about the bottom, waiting for spring to return.

As for their immune system being weaker in the spring - that is the common wisdom, but again good water quality will keep them healthy. Lots of people feed their koi garlic as an immune booster, but again - the fish are doing what they normally do. If the water quality is good, they will come out of winter just fine.
 
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Only my opinion, but I believe large koi need additional O2 during the winter. How you achieve that varies. As @Lisak1 suggested, keeping your pond running through the winter, is one way. Suspending air stones a foot or so into the water, in addition to keeping a hole open is another way.

You might be interested in reading @callingcolleen1 thread on how she winters her large koi in Canada.


If you read through her entire thread you'll discover she now covers her ponds. I have 4 large adult koi and began covering my pond a few years ago. The cover prevents cooling through wind chill and reduces evaporation. I also suspend air stones about a foot in the water and run a Pond Breather.

I agree with @Lisak1 , wintering 25 koi inside, will be quite challenging. Lets see if we can't pool enough experience and information to help you over winter you koi outside :)
 
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I don't have koi, only goldfish, and our pond is covered in winter. That allows us to run the filtration year round and the pond never freezes with no heating added. The fish don't have to go through that risky time in spring when everything is starting up again. The beneficial bacteria may decrease, but it doesn't die off completely and it quickly recovers.

I'm not in Canada either, so that would make a difference as well. I was very surprised that we have had no ice whatsoever on the pond when it has been covered, even with single digit outside temperatures. Without the cover, the ice was at least 4" thick, enough to walk on.

These pictures were taken the same day, one outside, the other inside.

058.jpg
064.jpg
 
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I don't have koi, only goldfish, and our pond is covered in winter. That allows us to run the filtration year round and the pond never freezes with no heating added. The fish don't have to go through that risky time in spring when everything is starting up again. The beneficial bacteria may decrease, but it doesn't die off completely and it quickly recovers.

I'm not in Canada either, so that would make a difference as well. I was very surprised that we have had no ice whatsoever on the pond when it has been covered, even with single digit outside temperatures. Without the cover, the ice was at least 4" thick, enough to walk on.

These pictures were taken the same day, one outside, the other inside.

058.jpg
064.jpg
I am amazed when I peek under the cover in the winter ! Some of my hardy plants are still growing! The koi, while not nearly as active as in the summer are slowly moving around...more than when I left the pond uncovered. I wish I could keep my filter running, but our pipes are exposed. We're working on a new small bog, but don't have enough experience with it yet to know if it would help running over the winter.
 
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I agree. It's amazing how different it is inside. There is a water lily still growing in the picture of the pond inside the greenhouse cover.

My fish don't go into torpor like they did when the pond was uncovered. They are always moving around so I think it's probably much better for them to keep active like that. I even feed them all winter. Not a lot, but lightly each day or every other day, and I use a sinking food since they don't like to come up to the surface.
 
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Sitting and pondering all of this amazing advice and encouragement when the doorbell rang... It appears that the dye is cast, my adventure with koi in the garage at least for this winter is underway....
We are definitely planning to transfer water from the pond to our box. There is a drain in the garage that I am hoping will be useful for freshening up the water as needed. As per the instructions of @koiguy we are not planning to use a net to transfer the fish. He reports using a pillowcase or towels to lift the fish.
What is a pond cover? Is it a large sheet of plastic?
I definitely want to look into the additional items mentioned and I am planning to discuss all of this with my Amish next-door neighbor who is my ‘partner in crime’.
Thank you again and updates to follow.


7D4403E7-6D7B-44B9-815D-07644137DCBC.jpeg
 
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I don't understand where your fish will go or how you will use that frame. Is there a tank that fits inside it?

As for a pond cover, we build a greenhouse type structure over the pond. There are pictures of it in one of my posts above. It is made of a wooden frame that is covered with one layer of 6 mil plastic and a second layer of pool cover plastic. The pool plastic cover is very heavy and looks like bubble wrap.

We used to take it all down every spring and put it back up in the fall. But it tended to get larger and taller each year, so it has gotten to the point that we now leave the frame up year round. We remove the frame end pieces and the frame that goes over the waterfall. And we fold up the plastics so that there is only a small amount of the roof covered during summer. It's much easier to get it all covered again in the fall this way.
 

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How big is that frame? Your koi will need room to move as they are used to a 9000 gallon pond! Really think you are better to work on making your pond winter safe as opposed to bringing in that many fish
 
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Greetings, Mrs. Clem. I have not succeeded in keeping my large koi alive over winter here the last two years despite faithfully maintaining a hole in the ice and an aerator running under the ice. On visits to our local pond and rock shop I have heard that Koi in outdoor ponds died all over our area last winter. In any event, we are going to give this alternate approach a try this winter. Honestly, I had not realized we could keep our pump going under the ice as well, but we are going to run the pump in the garage plus run aerators. And, I will be able to remove and freshen up water as needed.
The pond frame will be lined with wood, an inch of insulation and a liner. The filter will be attached and the pump will be running. Next winter, when the fish are bigger, perhaps we will be able to do this and more in the outdoor pond. I would like to see photos of people’s pond covers. I think it would be quite ambitious to build one above our pond which is fairly large; my Amish next-door neighbor does love a challenge though. I have another reason for liking the pond cover idea — we have had our first visit from a heron this summer. Immediately covered the pond with a net for protection, but it is rather unsightly.
 
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Sorry but I just don't see this ending well. That enclosure can't be more than a few hundred gallons. You could maybe get by with a few fish in there, but 25? Water changes alone are stressful to fish - and you'll be changing water daily.

If the drain you're referring to in your garage is like ours, it doesn't actually go anywhere. It's just meant to capture small amounts of water and allow it to seep slowly into the ground under the garage. It wouldn't handle hundreds of gallons of water at a time. But maybe you have a different type of drain. What's your water source in your garage? Even in an insulated garage, at 20 below zero you may have trouble keeping a hose from freezing.

It sounds like you're intent on proceeding with your plan, but you did ask for advice. I'm sticking with my original thought - your assumption about why your fish are not surviving the winter is off base. There's something else going on with your pond.

What are the actual dimensions of your pond? How big are your fish? How many fish are you losing in the winter? How are you keeping the hole open? Do you get a lot of snow in your area?
 
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There is a woman on a koi forum who has a large pond. She covers a portion of her pond, with good results....and that is where her koi choose to be. I mention this as an option, since your pond may be too large to cover.

I will hope for the best outcome for you and your koi. Do you have a good water testing kit? If not, I'd get one , it'll be essential in monitoring your water quality given your fish load and water volume.

If you have time, I'd be interested in when and under what circumstances you found your koi died over the last couple of winters.
 
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I, too, have doubts about putting your fish in that small an area. It seems they would very quickly pollute the water in that small a space. Unless that frame is a lot larger than it appears, I'm not sure that would work very well.

Here are some ideas for putting a cover over a pond:



If you Google "winter pond cover" and click on "images" near the top of the page, you will find lots of ideas.

We can't leave our pond completely enclosed in the greenhouse in the summer. It would get much too hot inside. It is only for winter use, but the top of the roof is covered year-round. We also have shade sails over the pond and that has so far kept any herons away, knock on wood. There isn't much, if any, of the pond visible from overhead, so I think they help.
 
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If you had enough filtration, which would be a lot more than normal for that amount of water since the fish load is so high, you might get that to work. With the way it is constructed, though, I would worry that it won't be able to hold the pressure of the water. If there are not a lot more bracing and cross members, that frame is not adequate, in my opinion, for the amount of water that would be inside it. I would definitely test it outdoors and make sure the structure would be sturdy enough.
 
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mrsclem

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Agree with WaterGardener, the sides will bow out and the box could collapse. If you are determined to bring your fish in, I would consider an Intex swimming pool. Super cheap right now.
 

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