Blue Ridge Koi Blog

Posted by Casey LeFever

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Koi and Winter Hibernation

Did you know that koi hibernate during the winter?  Yep, just like many other animals, koi are very sedentary during the fall and winter months.

Now, to be clear, koi do not technically "hibernate" during the winter.  And their activity is not like other hibernating animals.  There is no burrowing, no hoarding of food, no stealing of pic-a-nic baskets.  But they go into a hibernation-type state just the same.

When the water turns cold, you will notice a dramatic decrease in the activity level of your koi.  They will "sit" on the bottom of your pond, floating upright with their pectoral fins tucked up underneath the body.  Their heart rate and metabolism slows during the cold period. 

Check out this video clip of koi in cold fall water.  (Sorry in advance for the bad cell phone quality).  Notice that while some of the koi are still moving slowly about the pond floor, others are already sedentary, floating in place with their fins tucked.

Hibernating Koi in Cold Fall Season Water from Blue Ridge Fish Hatchery, Inc. on Vimeo.

Koi should not be fed (and in most cases will not eat) when the water gets below 50 degrees.  That's right, they don't need to eat at all.  Koi will go through your entire winter season without eating pellet food added to the pond.  

Although koi can live through the winter in a frozen-over mud pond, it is a good idea to keep at least a part of your pond's surface unfrozen.  The climate that you live in will determine what you need to do to prevent freezing.  In some warmer climates, keeping the water circulating constantly may be enough.  Colder climates might require a heater.

If you have any questions, look for a qualified koi and pond dealer in your area.  Someone local will be best equipped to answer your questions about koi and the cold winter season.

 

 

Linda
Apr. 13 - 2014

When does koi hibernation end?

    Casey LeFever
    Apr. 13 - 2014

    Hi Linda,
    Koi hibernation ends in the spring when the water begins to warm. When koi are coming out of their version of hibernation, you will see them become more active, coming to the surface of the water and eating.

Jay
Oct. 06 - 2014

What if a koi is pregnant going into the cold season in PA?

    Casey LeFever
    Oct. 07 - 2014

    Hi Jay. It is not likely that your fish is gravid (carrying eggs) at this time of year.

Anonymous
Oct. 08 - 2014

Casey, The fish looks fat from almost head to tail. It really looks stuffed. It looks nothing like the other fish in the pond and there are many. Thanks

Jay
Oct. 08 - 2014

Hi Casey. It sure seems like she might be. She looks fat from head to the rear fin. There are a lot of fish in there and I don’t thing she can compete with the other fish that much so that she would be that overweight. Interesting though thanks.

Howard
Nov. 08 - 2014

How can you tell which type of Koi you have (they were all in the big pond when we purchased it in 1997).. There were five now down to three (no idea what happened to the two). One darker orange and one lighter orange and one white. All about 18 inches minimum length.

    Casey LeFever
    Nov. 10 - 2014

    Hi Howard. There are multiple variety guides online that will help you to determine what variety of koi you have. Thanks.

Mark H
Nov. 13 - 2014

Awesome

Anonymous
Nov. 15 - 2014

I put my Koi in a 5 foot square plastic container that is perforated with 2 inch holes for water circulation. Then I sink the plastic box in the lake in 8 feet of water.
I have done this for many years as soon as the water temp goes below 40 degrees.
I just put them in the lake in central Ontario Canada this past week.

Anonymous
Nov. 22 - 2014

Hi. I am fairly new to koi keeping. I have had my pond for just over a year and this will be the second winter. Last year I was unable to see my koi shortly after winterizing the pond as the water clouded up, so I only got to see a little glimpse of what they are like when they start hibernation. This season, the water is still crystal clear :-) and I can see them pretty well. I go out to check on them and they still make an effort to swim up to me. They also like to swim up to the shallow end of the pond at night and huddle together. They only go down to the 4 foot section during the day. I am wondering if all this activity is normal for their hibernation stage? The water temp is 37 degrees. I would think they would stay in the deep end …..????

    Casey LeFever
    Nov. 24 - 2014

    Yes, that activity is normal for koi during the cold winter months.

Nancy
Dec. 07 - 2014

We have one of our koi about 6 years old 16 to 18 inches long acting different from the other 15 koi . They are all at the bottom of the pond where they are moving around some. He is on his side and back breathing shallow not like the others. He doesn’t look right. With the snow , ice and a long winter coming . My big fear is he is sick which is a sad thing but I don’t want to leave him in . I’m worried I might lose all the koi by next spring . We can get him out if we need to ,so we can protected the others!!

    Casey LeFever
    Dec. 10 - 2014

    Hi Nancy. Sorry to hear that. It would probably be best to remove that fish from the pond before it freezes over. Good luck.

Kevin Nichols
Jan. 10 - 2015

I have 3 koi 8 gold fish all goldfish are doing 2 koi acting very weird 1 floating appears to be gasping for air on top floating the other koi much larger on bottom of pond lying on side moving around a lot 1 koi seems unaffected by the cold and seems to be concerned for his fellow friends more than anything is this normal I have had fish for 2 years and take care of the water very well with proper water balance with pond products etc. have water features spitters ,eratores.sorry for my spelling I do have a heater but haven’t used it since fish didn’t seem to bothered last year water temp.39 and outside has been 50-60 days and sometimes high teens at night.

Anonymous
Mar. 01 - 2015

HI MY NAME IS RHEA. WE HAVE HAD A LARGE KOI POND FOR YEARS. WE LIVE IN WVA, AND AS YOU KNOW THIS HAS BEEN THE COLDEST WINTER AS FAR AS TEMPS,IN YRS, I USUALLY KEEP THE WATER RUNNING IN POND IN THE WINTER, BUT IT FROZE UP THIS MONTH AND I HAD BACK SURGERY AND I HAD NO WAY TO TAKE CARE OF OF IT, WE FINALLY GOT A CHANCE TO DE THAW THE ICE AND GET PUMPS TO RUNNING AND ABOUT 5 LARGE 8 TO 10 LB KOIS WERE FLOATING WE THOUGHT THEY WERE DEAD SO WE TOOK THEM OUT THE POND, THEY DONT LOOK DEAD NOT STIFF THEY DONT APPEAR TO BE BREATHING, SO WE LAID THEM ON THE SNOW FOR ABOUT 10 MINS,AND NOTICE ALITTLE BLOOD COMING FROM THE MOUTHS. NONE OF THE SMALLER KOIS SEEM TO BE BOTHERED.WE HAVE SEEM KOIS HYBRNATE IN THE PAST BUT DO THE LARGES LOOK DEAD AND FLOAT, OR COULD THEY JUST BE DEAD

RAY
Mar. 01 - 2015

WE HAVE A LARGE KOI POND WE HAVE HAD IT FOR YRS, THIS MONTH IT FROZE OVER AND I HAD BACK SURGERY, I COULDNT GET OUT TO KEEP THE PUMPS RUNNING, FINALLY MY WIFE AND I GOT THEY PUMP OUT AND RUNNING, ABOUT 5 OF OUR LARGER 8 TO 10 LBS FISH FLOATED TO TOP, THEY ARE NOT STIFF WE TOOK THEM OUT LAID THEM ON SNOW AND SOME BLOOD CAME OUT THE MOUTHS, SO WE PUT THEM BACK IN, I HAVE SEEN THEM HYBRNATE BEFORE, WE ARE SCARED THEY MAY BE SOME LIFE IN THEM, OUR SMALLER ONE DOESNT SEEM TO BE AFFECTED. DONT KNOW IF WE SHOULD TAKE THE BIGGER ONES OUT OR LEAVE THEM IN FOR A WHILE LONGER

    Casey LeFever
    Mar. 01 - 2015

    Unfortunately the larger fish that you described are likely not going to make it through the winter. We would advise to remove those fish from the pond and dispose of them. Sorry for your loss.

RAY
Mar. 01 - 2015

thankyou so much that is what we are doing now, its just hard we have had them many many years

Anonymous
Mar. 05 - 2015

My koi are not moving. They are at the bottom of my pond under some lilly pads. The water is really cold and they are facing the same direction. Is this normal?

Anonymous
Mar. 05 - 2015

I do not know if they are hibernating.

    Casey LeFever
    Mar. 05 - 2015

    Yes, that is quite normal for koi in the winter time.

Anonymous
Apr. 03 - 2015

With the unbelievable conditions in the north east this winter I am sure many will be facing the sad prospect of dead fish. I have had a pond for 20 years and this year was the worst I have seen. I just took out four of my largest Koi that died over the winter.
The problem was not suffocation. It was from the snow being so deep (8 feet in Boston) that they were crushed by the weight. Add to that the bitter cold of 15 below for weeks.
I am really surprised that any survived. With that being said you will find Koi are very hardy and can adapt to sever conditions.
Try to get as much water movement as you can early. It might not be time for your big pumps but remember the pond needs air. Aerators need to be open wide. This will also help in clearing ice and snow from the pond. Don’t forget about a micro lift once the temps climb and a partial water change. These will give them a fighting chance after a long winter.

Anonymous
Apr. 10 - 2015

Hi my koi is in the shallows ar side of pond , not swimming around unless I move him
He then swims off normally but always returns on the ledge not moving , I’m concerned he is sick

Casey LeFever
Apr. 11 - 2015

What is your water temperature currently?

Anonymous
Apr. 13 - 2015

I have a koi doing the same thing. Staying by side of pond, but swims away when I start to look. No injuries. Pond is about 50. Other Koi swimming like crazy, I think they are spawning.

Anonymous
Apr. 13 - 2015

My fish is doing the same thing. My water temp is 50. All other fish are fine, but I know they are spawning.

Eric
May. 13 - 2015

last year we added koi to our pond. Followed all the steps for a healthy strong Eco system within the pond. Spring, Summer, and Fall were all great. We then prepared for a MN winter w/ a heater. I checked weekly, making sure there was always an open portion on the pond. After winter into spring (previous 4-6weeks) I have followed the steps, etc. only 1 problem, I have not seen any koi yet? Is this. Normal? I would say the filter/waterfall has been on 24/7 for the last 12 maybe 13 days. Water temp has not dropped below 55, currently is 61. The water is clear and looks good, I do have some algae on rocks in the pond. Other than that , all is well and normal. Except no fish yet? Any ideas? Went into winter with 4 koi.

    Casey LeFever
    May. 13 - 2015

    If you have a large and deep pond, it is likely that they are still lying dormant near the bottom, out of sight.

Eric
May. 13 - 2015

This could be very likely the case. If it is, at what water temp and/or condition(s) will these guys “wake” up from their nap?

Thanks.

    Casey LeFever
    May. 13 - 2015

    They should come around once the water temperature is consistently above 50 F.

Sarah
Oct. 03 - 2015

We have 3 Japanese Koi and in the last two weeks their actvity has noticeably decreased and they are not very intersted in their food. they eat some of what we give them but they are not eating much. As this is the first time we have looked after them i am surprised how early they seem to be going into hibernation. Is this normal? We are in London England where we have had a few days of indian summer but are generally having Autumn weather already.

Thanks

Anonymous
Oct. 05 - 2015

Hello, I have begin to notice a decrease in my Koi activity as well. IS it normal for them to begin “hibernation” this time of year? I live in NY and the weather is now turning cooler only reaching about 65 degrees each day

    Casey LeFever
    Oct. 05 - 2015

    Yes, it is normal to see a decrease in the activity of your fish during this time of year.

jamie
Oct. 19 - 2015

It got colder in NY early this year. My koi are in the garage and water is mid 40s so they dont eat. Will they make it from October to probably late April without eating anything?

    Casey LeFever
    Oct. 19 - 2015

    Yes, if the water remains that cold for the entire winter, you should not feed the fish and they will be fine until the water warms again next season.

Anonymous
Oct. 25 - 2015

We have 6 baby koi that are about 1 1/2 inches. Our pond isn’t very deep so we move our koi into the garage in a horse tank. The water stays in the 30s and never freezes. Should we bring the babies into the house and feed all winter or will they be able to hibernate with larger koi?

    Casey LeFever
    Oct. 26 - 2015

    Fish that small would likely be better off indoors, as opposed to trying to overwinter outside.

Anonymous
Oct. 26 - 2015

My father has a 20,000 gallon pond with many Koi, he had babies this last spring & we brought 20 of them home to grow in a tank. They are still fairly small & have acted normal up until this morning. Now they are acting sedentary, they are all schooled up, don’t want to eat, etc. So I guess my question is will Koi still hibernate in a tank where the water is kept at approx 78 degrees?

    Casey LeFever
    Oct. 26 - 2015

    No, koi will not hibernate in an indoor temperature controlled tank. There is likely another issue causing behavioral changes in your fish.

Anonymous
Oct. 26 - 2015

Thank you for your response, I am unsure of what else may be going on as they have been acting fine & this afternoon they seem to be more active & eating! Hibernation was just a thought & I wondered if somehow they might have a natural instinct to know that’s what they should be doing at this time of year!!

Anonymous
Jan. 24 - 2016

I had 4 inches of ice I had on my small koi pond when I got the ice of pond I noticed that 3 of my 3 pound koi were floating belly up and the 4 one is ok is there anything that I could do to help them ?

    Casey LeFever
    Jan. 25 - 2016

    Sounds like your fish may have suffered from a toxic buildup of chemicals under the ice. The fish floating belly up are likely dead and cannot be saved. Here is some information on ice and koi ponds.

Anonymous
Feb. 12 - 2016

We have been having a lot of spring like temps in Oklahoma for the last few weeks. The water temp in our koi pond is 50 degrees today and we are seeing lots of “bubbles” on rocks and some plants in the pond that look very much like eggs! Is it posslbel that our koi have spawned. On the really warm days they have been fairly active.

    Casey LeFever
    Feb. 29 - 2016

    If the water temperature is warm enough, it is possible that your fish spawned. 50 degrees is likely not warm enough however.

Jac
Feb. 12 - 2016

Is it possible that our Koi could have already spawned even though it is still February? We have had unseasonably warm weather for weeks in Oklahoma and today we are seeing lots of Bubbles on the rocks in the pond that look a lot like eggs!

Ryan
Feb. 17 - 2016

2/16/16 Hello…we have been raising koi for 20+ years and just yesterday had one mysteriously die. We are in york pa and the weather has been very out of the ordinary this year…several days in Jan. and Feb in the 60′s and then back to 10 degrees. The large koi that died looked oddly fat for this time of year…we removed it and checked its belly to find out she was full of eggs. Is it possible that due to the extreme temperature fluctuations the fish thought it was time to spawn 6 weeks before It actually was time to, and went back into hibernation? There were definitely periods this winter that they were very active and looking for food. We keep 2 bubbles and a heater running so the surface never freezes over.

    Casey LeFever
    Feb. 29 - 2016

    Yes, it’s possible that the fluctuating temperatures deceived your fish into thinking it was spawning season.

jim
Mar. 16 - 2016

Casey whats the best method in checking water quality .

    Casey LeFever
    Mar. 17 - 2016

    There are multiple test kits available to test pH, ammonia, nitrite and other water parameters. Any well-reviewed test kit on Amazon should do.

Danielle
Apr. 01 - 2016

Hello, my koi made it through the winter and now that they are active again, they won’t eat. I’ve had 5 die over the past 2 weeks. Water was tested and is fine. Do you know why this would happen?

    Casey LeFever
    Apr. 01 - 2016

    No, sorry, we are not able to speculate on what may be affecting your koi.

Anonymous
Apr. 04 - 2016

we moved and so we need to move our koi to their new home. Is it ok to move the koi just as they are coming out of dormancy?

    Casey LeFever
    Apr. 04 - 2016

    Moving fish just as they are coming out of the winter will increase the risk of health complications.

Anonymous
Apr. 16 - 2016

I am thinking of adding two small koi (~3″) to my small pond (~8X10 and 3.5 feet deep) which at present has 9 large gold fish (all about 10″ and happily live through winters in our garage.) Is this an okay idea? Will they eat the same food? I usually start with flake good in the spring then switch to pellets. Is this good for koi and gold fish?

May. 05 - 2016