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?

Merri
Sep. 26 - 2016

Do Koi come out of hibernation on warm days after the first cold day? Mine disappeared on the first cold day but it’s been warm since and I haven;t seen them…

    Casey LeFever
    Sep. 26 - 2016

    Yes, koi activity will fluctuate as they move from one season to the next. They will be more active on warm days as the temperature increases, and then less active as the water cools.

Merri
Sep. 27 - 2016

I guess I’d better go look for them. I haven’t seen them since that cold day and it’s been quite warm since…:(( Thank you

Anonymous
Oct. 23 - 2016

Hi I am a teacher and live in Georgia. We have a small koi pond at our school and have no idea how to winterize it. We are told we can run the pump all winter since we are in the south. What should we be doing right now. I did clean the pond on yesterday. No dead leaves and will trim the lilly down on Monday

Anonymous
Oct. 23 - 2016

how do we winterize in the south

Casey LeFever
Oct. 24 - 2016

Here is some information on how to properly winterize your koi pond – https://nextdaykoi.com/koi-how-tos/overwintering-koi-fish/

Anonymous
Dec. 10 - 2016

Hi, it’s 27° my pond is frozen over but the pump is still running and has part of it that’s not frozen. Is it normal for the Koi to be laying on their side or belly up at the bottom?

    Casey LeFever
    Dec. 10 - 2016

    No, it is not normal for the fish to floating belly up or laying on their sides. They should be upright, on the bottom of the pond.

Anonymous
Dec. 14 - 2016

My koi were happy in their cave and today I lost one and now they are all out of the cave, swimming and even coming to the decider rings . I am scared that more will die. I had 2 bubblers and the falls are still going. I must admit I have not been as regular as summer with my cold water bacteria. I added some today. Did I kill my fish? Heartsick.

Anonymous
Jan. 06 - 2017

Good Morning,
I so enjoy my koi and gold fish. I didn’t want to chance the winter there for I placed a portable green house over my small ponds. This kept out all fall leaves of fall. With the green house the water temp. has stayed between 60 & 68 degrees depending on the outside temp.
Will it harm my fish not to take the winter rest?

    Casey LeFever
    Jan. 07 - 2017

    No, your fish will be perfectly fine if they skip their winter rest!

Anonymous
Jan. 23 - 2017

Awesome Blog!
I am relatively new to keeping maturing koi (3-4 years old) now that I have 2 6000 gallon ponds connected by a river. In my Upper Pond I have lost 3 of our 14 bigger ones in the past 3 days, as they (only about half) started getting a bit more active with 10’C (50’F) days. (GVA – Greater Vancouver Area, Canada). I know that you (Casey) CANT hazard a guess to why they died, but can you comment on some of my ideas?

Notes/Questions
1/ perhaps I killed them with love, as I had a hose running all winter long (low chlorine/fluoride levels here). Non the less perhaps the water was TOO “Clean” (though no problem running the hose at full for days/weeks in the summer)

2/ All that died were getting more active then the others and coming to the top (5 of 14) … 3 died 2 WERE critical. I am quite sure it was NOT Oxygen Problems from the pond itself.
2 of 3 that died I got them and put them in my 300 gallon Solarium Pond (20’C – 70’F) propping them up to not go upside down – sadly both died within an hour – though comfortably.
Q? I know fish can/WILL be shocked going quickly to new temps, but last year in October I got 40 “Problem” Koi (blind/half blind/Mutated in some way and successfully put them in the lower pond late in the day QUICKLY by individually SLOWLY lowering them into 10’C/20’F Colder water SUCCESSFULLY!
Is this a known method?

and just FYI the 4th of 5 sick went upside down for a second and I got him right away and propped him up in the warmer Solarium Pond and he is upright on his own this morning – LIVED Through the night listening tho the CBC. I would bet he will be fine!

3/ I put a hose in the upper pond with FULL HOT water at noon yesterday (and even put the HOT water in my Underground waterfall/filter return and unblocked the ice and got it running too. Within less than 2 hours I got all three pond areas from 6’C(40’F) to 10’C(50″f) and with in the next 3 hours to 20’C(760’F).
SO FAST and easily! Now just 1/4 bhose pressure is keeping it stable!
Q?/ I guess now I NEED to keep it above 50’F, as to not put them back into hibernation Mode.
Is this correct?

4/ the 5th is doing much better last night and this morning in the warmer water!

5/ In thinking that the water was “Too Clean”, I added dirty/smelly/bacteria-filled filter water from my small Solarium pond to the outdoor warming ponds.
Is this a good idea, or what? LOL.
Today My Fatty was rummaging the bottom looking for his “Yogurt” – AWESOME!

6/ and Final note. In my Small Solarium pond I had 14 small koi (less than 3-4″) over this winter. I let the water dip slightly below 10’C(50’F) for a week over Christmas and lost 3, with a few more looking bad (gill problems and/or skinny issues, but I have kept the water above 20’C(70’F) since then and all is well! and now Whitey-Black 18″er has joined it, and I call it my “Solarium Hospital Pond”, as I already stated – I finally saved a “Critically” Sick 18 Incher!

7/ and just FYI, my Larger Koi are mostly over 2 feet in 3-4 years! …
… They have been fed primarily Dry Dog Food, and natural pond vegetation (ex. Duck weed from my bog)
DOG FOOD! against all advice has proved awesome – protean and all!
(my ponds/river/bog/waterfall/water-gardens NEVER gets dirty – period, rotting dog food and all)

    Casey LeFever
    Jan. 23 - 2017

    Sorry, not sure what your problem might be. There are several active koi groups on facebook that would be happy to help you out.

Mark Ackerman
Jan. 23 - 2017

Just an Update, for others that may be interested,

One more went critical this late last night, which makes 3 in my Hospital Solarium 300 gal./with Warm/Clean/Oxygenated/Good-Bacteria Water with the 9/14 growing Babies that made it thus far and thriving (now all 5-8 inches!).

As the Outdoor Ponds have been 20’C/70’F for 24 hours with Waterfall/Filter and probiotics added, and I cleared many obstacles as the “Sick” Koi are definitely having vision problems … I decided to put the 2 doing better after just 12 hours in the “Hospital”, (I put) them into the waterfall section of the Upper Pond, and 1 (upside down this morning) is seemingly back to Visual and Swimming normally and reasonable actively at the bottom (WooHoo) – Out of Critical it seems.

The Second which was in the Hospital Pons overnight and is struggling to stay upright 20% percent of the time in the hospital is doing MUCH better in the Upper Pond too, and has found a ledge under the waterfall and resting happily there and swimming mostly close to the top still, but has returned twice to the same ledge – WooHoo!. I mention this, as I think whatever their problem is, it includes difficulty getting Oxygen. I will restate that there has been flow all winter, with minimal decaying plants, and always most of the surface clear of ice. This leads me to the present new conclusion that they have some d”Disease”, which is at least effecting the gills.

Having the waterfall/filter working with the hot water now turned to 1/4 pressure is awesomely allowing for 17-20’C(65-70’F) well Oxygenated and Clean Water Flow – Amazing as last night was below freezing and the high today (and seasonal) is approx. 6-9’C (43-48’F). As a “Rocket Scientist”Pilot/Chemical Engineer with a twin brother as a Veterinarian … I am amazed that ~ 15,000 gallons of Waterfall/Pond/River/Pond/Bog can and is warmed up so easily!

WooHoo! I will have to reassess Thermodynamics of Water!

Just FYI, a pretty cheap solution with 3 of 4 off critical. (One still in the hospital not getting better … only worse)

and another point I newly noticed is that any sick fish with good gill action was a lot more likely to get better in the hospital, and minimal gill action means sadly likely a lost cause.

I hope this helps others. Mark

Mark Ackerman
Jan. 24 - 2017

Last Update:

The Koi I got to too late passed sadly but on a Happier Note,
the 2 put back in the pond have regtained full sight and are swimming at the bottom NORMALLY and with the school even!! And the last Top swimmer on sick list is also back to Normal with the other six (9 total in Upper Pond) all schooling and even rummaging! and have gone to the waterfall sub-area during the day as they love to do all summer.

What a change in just 2-3 days!

Warm water running in keeping water at ~17’C(65’F) , biotics added (through filter scum), clean soil added, and Filter/Waterfall running full time …
… Have done the trick!

Just FYI, Mark …. WooHoo!
p.s. By next winter I pla an inch of sediment on all my Rubber floors which I bet will make their winters MUCH More Bearable.

Anonymous
Feb. 15 - 2017

Hi, We live in Michigan our pond is 20 X 20 ft deep with a side jet, bottom drain, Settlement tank, KOI AIR 1000 aerator from the bottom, skimmer, waterfall the whole deal, just about a swimming pool :-) – My concern is this years winter has gone from 12 below to 60 degrees. Last year I had zero issues they all stayed at the bottom and spring they magically appeared. This year I lost one and noticed the others were more active at the bottom. Again this weekend we are expecting 60 degree in February! I am so worried this is going to take them out of their current state then it freezes again. Any suggestions or should I not be concerned? – Thanks Michelle

    Casey LeFever
    Feb. 15 - 2017

    Hi Michelle. I wouldn’t be overly worried about them. Losing one fish during the winter is not abnormal, as winter is a stressful time for koi. Here is some more information on deicing and aerating during the winter months – https://nextdaykoi.com/koi-how-tos/koi-pond-deice-or-aerate/

Anonymous
Feb. 19 - 2017

It is February the 19 it is not freezing cold my gold fish are swimming about sad to say my lovely Koi looks like he is on his side he must be at least seven and his weight must be ten pounds what should I do as he is still alive

Nina street
Feb. 19 - 2017

It is February and a nice sunny day my goldfish are swimming about but my lovely Koi is lying on its side. It is still alive but cannot stay normal. He is about ten pound in weight. I have not feed them since last October. Can you tell me the beat thing to do to save him my pond is very clear and has no enemies to kill the fish and the pump has been on all winter the pond is built above ground and been going for nine years Please help

    Casey LeFever
    Feb. 19 - 2017

    Sorry, there’s not enough information here to diagnose the problem. Please try contacting a koi dealer or pond shop in your area for help. Thanks.

Katie
Feb. 25 - 2017

With the incredibly warm weather…temps in the 70s all week and 80
Yesterday, my koi are very active. I put Spring food pellets in the
Pond and they were all eaten. I know I shouldn’t feed the fish, but I hope I haven’t
Endangered my fish since I know it will get cold again. How bad is it to feed them
Now?

Anonymous
Feb. 25 - 2017

I am having similar issues as a few above. Live in MI and I have had success for the past 4 years wintering my fish outside with zero deaths. Most of my fish are Shubunkin goldfish and about 6 frogs. My pond is only about 3 1/2 ‘ deep. This Feb. we had a very warm spell and many of them came out of the “hibernation” state and began swimming under the ice. I worried and now with good reason. So far I have lost 4 to 6 fish . We are headed back into a cold spell. Questions: 1) do you think they are dying because they came out too soon can’t handle the temp change 2) will they go back into the dormant state with the resumption of the frigid temps. The majority of those lost have been my new spring ’16 fish but now one of my 3 to 4 year old beauties has died. HELP

Feb. 27 - 2017