Koi died in winter

[Beth Feldman]

I live in Upstate NY. My pond is 10x12 x5 feet deep. I had 6 large koi that had over-wintered 3 winters. I use a bubbler or a stock tank heater to keep a hole in the ice. This winter 5 out of my6 koi died (all the same day). There was about an inch of ice over the pond, but the stock heater was maintaining a 5" hole. I saw a couple of fish up at the hole just before they died. Any idea what happened?

[j.a. frias]

so sorry!!!

[luckyd]

For five to go in one day I would look into maybe electrical issues from the heater. What is your water temp? Cold water is hard on the koi, but yours have been thru it before and have made it. With that said, I would check all your water parameters and also check the remaining fish very close. Sorry to hear the bad news.

[Gee]

Very Sorry Beth..... this year the same happen to me..... i lost 22 large koi... very bad winter here in Mi....

[j.a. frias]

So sorry Gee , i still like looking at the pictures you posted simply perfect koi

[Bill Bell]

Dear Gee, That's a terrible loss...22 large koi...We (Massachusetts) also had a terrible winter, I had cancer so I was attempting to tell other people what to do with the pond. With ice almost a foot thick I feared the worse, but was very lucky in that I lost one Shubunkin and all the koi were still alive. Why? I do not know. I hope you have better fortune in the future. Bill

[Darrell Goeken]

Beth. How clean was your pond bottom going into winter? I ask because even an inch of wastes will start to decay and cause a spike in Ammonia, and carbon dioxide levels as well as a increase in the water temperature, and drop in the PH. It may also increase hydrogen sulfide. All of these are toxic to our wet pets. I don't know if this is what happened in your pond, but it's a very probable answer for many ponds with unexplained deaths. The wastes in the decomposing process can also raise bottom temperatures rapidly into the 70s for a period of time.

[Cindy]

A 5" hole is too small. My guess is CO2 poisening. You may have got away with it past winters because the koi were not quite as large or there may have been better gassing off, but the fish being up at the hole and since last winter was a bad one, the 5" hole didn't cut it anymore. I'm so sorry you lost your fish.

Cindy