Koi sleeping on its side

[Sushi Prohibited]

It's winter and the koi are hibernating.
The water is 40 degrees.
Of my 10 koi, one of them is sleeping on its side with a very slight bend in it's body. It has been doing that for a week.
This is my 11th winter with the pond and fish and I've never had this happen before.
Should I be concerned or does he prefer sleeping on his side like me?

Thanks.

 

[Lisak1]

Well, fish don't "sleep" per se, so no he's not just a side-sleeper. The bend in his body is concerning as that can be a sign of illness or injury.

How big is your pond? What kind of filtration? Do you shut down for winter or keep the pond running?

 

[Sushi Prohibited]

4500 gallon
Water fall is still running as is the Savio skimmer filter.

 

[JamieB]

Can you nudge him to see if he reacts? Might be the long forever sleep.

 

[Sushi Prohibited]

I nudged him and he swam away.

 

[JamieB]

Fish are weird on occasion.

 

[WaterGardener]

Some fish don't respond well to cold water. They need to be brought inside for winter and provided with warmer water than they would have in the pond. I know of several people who have this issue with specific fish. They keep those fish inside, usually in a garage, for winter, then return them to the pond in the spring.

 

[Vita Powlsion]

I dont really understand,when I read people saying bring the fish inside for winter, I'm sure you all know how big koi get. And when you have a large pond trying to catch them is a hole nutha level. Where does one put them inside? And what do they put them in?

 

[WaterGardener]

Some people build an inside pond for them, some more elaborate than others. Other people use a temporary Intex type pool for them. Some use the larger water troughs, like ones from Tractor Supply, especially if it is only a couple of fish. They usually have at least two inside, since they feel the compromised fish needs some company. All of those set-ups need adequate filtration to keep the water in good shape.

The people I'm aware of who do this either have a basement to keep them in, or house them in their garage.

Some folks even bring in all their fish for winter.