Can large koi endure extreme low water temps.

[big ron]

I live in zone 7a and have 7 large koi in my pond that I have had for 15 years. My pond is covered with a PVC frame and clear reinforced poly. I have 2 aerators and a heater to keep the pond from freezing . The temperature here has been as low as 4 degrees in the mornings at times . Can these koi with stand this kind of extreme cold ? I have never seen it this cold for so long . Need advice please.

 

[j.w]

I live in zone 7a and have 7 large koi in my pond that I have had for 15 years. My pond is covered with a PVC frame and clear reinforced poly. I have 2 aerators and a heater to keep the pond from freezing . The temperature here has been as low as 4 degrees in the mornings at times . Can these koi with stand this kind of extreme cold ? I have never seen it this cold for so long . Need advice please.

@callingcolleen1 has a whole bunch of posts on her pond in Canada where she uses a cover in winter as you do: https://www.gardenpondforum.com/threads/my-pond-runs-all-winter-zone-2-3.10570/

 

[BKHpondcritters]

The fish aren't immediately affected by the air temp, as long as they can hunker down in the bottom of the pond where the water will maintain a cold, but not frozen, layer. The thing you have to make sure of, is that your aerators aren't in the bottom & stirring up the water which will disrupt the layering of temperature that happens.
My koi are down under the ice at the 3' deep level in the middle -

After yesterday's snow -

Temperatures are supposed to moderate a bit this coming week, so I'm hopeful we'll have enough thawing that I'll get to peek in & see them! But I'm not anticipating any problems.

 

[Tula]

I'm in zone 6B and wintered 4 adult koi in a covered pond with aerators suspended about 10-12 inches into the water and they did well. We closed our pond a couple years ago.

 

[mrsclem]

I'm in your area and kept koi for over 20 years. Pond breathers and heavy duty heaters if it got really cold. Never lost a koi to winter. This year it's goldfish only except 2 small koi. Never got breathers in and ponds are frozen over. No way with the ice to get down but underwater cameras show everybody is doing good.

 

[big ron]

I'm in your area and kept koi for over 20 years. Pond breathers and heavy duty heaters if it got really cold. Never lost a koi to winter. This year it's goldfish only except 2 small koi. Never got breathers in and ponds are frozen over. No way with the ice to get down but underwater cameras show everybody is doing good.

Yes we are neighbors. I am in Fallston, Thank you for your advice . Good to know that hopefully all should be fine. This is definitely a winter to remember.

 

[big ron]

@callingcolleen1 has a whole bunch of posts on her pond in Canada where she uses a cover in winter as you do: https://www.gardenpondforum.com/threads/my-pond-runs-all-winter-zone-2-3.10570/

Thank you I will definitely look into it.

 

[j.w]

Thank you I will definitely look into it.

She also has a youtube channel that I enjoy watching. She doesn't post as many vids as she used to on there tho but she has a ton of old ones. https://www.youtube.com/results?search_query=colleen+penny