How cold hardy are koi?

[greenthumbnails]

My Dad lives on the west side of Florida by the Tampa area.  This winter we had an extended cold snap.  Not just one but many.  He went away for about a week and returned to find a few koi dead, but the fancy goldfish and talapia still alive.  I figure the fancy goldfish are cold hardy and probably the talapia, but what about the koi?  I was thinking about buying him a heater, but even if I fork out the money to buy him one, he won't pay for the electric bill...He's only got 2 koi left  . 

[Sunbeam56]

Tilapia are much more cold sensitive than koi. If the tilapia survived, the koi should have also.
I'd look for a different reason that they are dying.

Usually, with koi, it comes down to water quality.
Tilapia are trash-loving fish and can live in filthy water that koi will not.

[greenthumbnails]

hmmm-maybe there was too much salt in the water...its from a well that he dug...says its a little salty...

[Mikos]

As someone from the North....I can attest that Koi are VERY cold hardy.  I guess if they aren't used to it and it comes suddenly then it might prove more problematic, but when the cold is gradual, mine survived under the ice without problem.  (the oldest Koi are 12-13 years old and this was the 2nd winter I've left them out).

[PondmaninAL]

I moved mine from down around Ocala, FL to up here near Birmingham, AL around the first of November. They went through Winter well.

[greenthumbnails]

Wow- I didn't think they could survive under the snow and ice!  I guess it was the water quality then...

[Mikos]

Wow- I didn't think they could survive under the snow and ice!  I guess it was the water quality then...

Amazingly my pond still gets a lot of leaves & branchs from the Willow trees that surround it and my filtration is pretty lacking.  I'm hoping this year to have a new filtration set-up to handle any water quality issues I may have.

Once November hits, I only run my waterfall pump (which usually keeps a hole in the ice as the ice forms around the waterfall)


As well I throw in a cattle trough heater as well to ensure that there is a hole in the ice. 


Now the pond is roughly 5000 gallons and I only have 19/20 fish in it (17 Koi and 2 or 3 goldfish) so that probably helps in that it isn't overpopulated. 

There have been a few of us Manitoba ponders who have started keeping our fish outside during our "rough" winters and interestingly the fish are doing pretty well considering the temps.

[jennyb5149]

To all you Canada ponders who overwinter your koi, how deep are your ponds? 

I have 3 brand new koi (ranging from 4 to 6" in size).  I'm wondering if I dare try to overwinter them in the pond this year.  I live in Northern Wisconsin (zone 3) where the coldest it will get is probably -15 to -20 F (don't get me started on the windchill tho  )

My pond is about 32" at it's deepest.  I wasn't planning on keeping koi when I dug the pond otherwise I would have went deeper to ensure overwintering would work for the fish.  oops!  Usual beginning ponder goof up, I guess!

[KatFish]

I think it depends on how deep your ground freezes.  In my neck of the woods, 3' is fine, but I went a little deeper just because. 

[Mikos]

I've been told that in our region, it's best if your pond is at least 6 feet deep.  However mine is 4.5 at it's deepest and I've never had a problem.  Even before I started overwintering outside, I'd check the pond and just running the falls, kept it from completely freezing.  Probably helps that it's pretty sheltered from the wind.  My fish have been outside for a brutal winter (2009) and a decent one (2010) and both seasons they did quite well.

I'm not sure if under 3 feet would be sufficient for overwintering purposes.  Probably best if someone from that area advises.