Newbie with major winter kill

[ReadLisaScott]

Hi all, so my aerator quit mid-winter and my koi pond (watergarden) froze over. I don't know how long it was out before I discovered it. (We had a brutal winter in upstate NY this year.) Once I discovered it, I had someone cut holes in the ice every other day or so to let the gasses out, but I knew it was a long shot that the fish would be ok. Well, now that the ice on the pond is thawing, I'm seeing all the dead fish and frogs. I don't know for sure if they've all died, but I've scooped out at least 75% of the medium and big fish I remember having. There's still a lot of ice on the pond. I don't see any signs of life. I'm scooping out the dead animals and burying them.

So, I'm wondering how to move on from here. (Besides crying for a few days. Some of the fish are ones I put in the first summer I built it--2008--and babies that were born in the pond.) Do I need to totally drain the pond to remove any bacteria from the dead fish? Partial drain? Or should I treat the water in some way?

My pond is 20 x 20, 5000 gallons, so no small feat emptying it. Also, how do you all handle gas release in the winter? Guess I'll need to use two aerators in the future. Thanks for any input.

 

[ReadLisaScott]

Oh, one more question. Do you think my water lilies and lotus will be effected at all?

 

[sissy]

They plants may have frozen and that will be a wait and see .It is sad but you really should have a pond heater and an air pump .I just bought the laguna 45 for 123.64 from wayfair on ebay .Maybe if you had babies they survived but you will have to get all the dead critters out fast to see if anything survived .I live in VA and have a pond heater and best investment I ever made .i just run it when needed .Really sorry about your lose

 

[Sunshine]

I used a pond de-icer also. Just plugged it in when needed. So sorry to hear about your loss.

 

[ReadLisaScott]

Do you think I need to pump the whole pond out to clean it?

 

[sissy]

That I think would depend on what you find as cleaning the pond you will be starting over .Have you tried testing the water and test after you get all the dead critters out and that may help you decide how far to go with the cleaning of it .Only you may be able to tell then .

 

[addy1]

A guy I know here lost all his fish, had a aerator running all winter. The best reason anybody could come up with, was the aerator was too large for the pond and the water was super chilled

So sorry you lost yours, he is devastated. but will restock the pond.

 

[sissy]

I bought a switched outlet for my pond heater so i can turn it on from inside and it sits over my pond pump and next winter will sit over my new air pump ,( proud of my air pump ) that's what you get from a ponder .polar vortex caused lots of problems

 

[Tula]

It's been a hard winter and many folks have lost fish. I'm sorry about your loss. I'm hoping you find some survivors and your plants survive.

 

[dieselplower]

Sorry to hear about your loss. I know how hard it is to lose fish under your care. I live in Michigan and for the past 2 Winters I have used a water pump with a fountain tube attachment aimed at the top, just with the actual fountain head removed. This creates a volcano like bubble of water shooting up to the surface. I have lost 1 fish in the last two Winters, and the hole has stayed open the entire Winter. There was a time during a very cold, windy, snowy period where I thought it was frozen over, but a poke with a stick opened up a large hole. Turns out it was just covered with blowing snow. This will still allow gases to escape. The reason I chose to use a water pump instead of an aerator is because I did not want to introduce air to the pond that could have been equal to the outside temperatures, which at times was quite a bit below zero. It sounds like you have a nice big pond. About how many fish do you have in there? It seems to me like it would take a good bit of time, or a ton of debris left in the pond before Winter, to cause the fish to do from ammonia poisoning or to die from lack of oxygen. When a lack of oxygen does occur, it is usually the big fish that die first, since they need the most oxygen to survice. As they die off, it leaves the smaller fish with a better chance of living. If I were you, I would get that ice melted by getting the water circulating, and then see where you are at. Examine the fish and see if they look like rather healthy, besides being dead of course, or if they look like they died from infections. If they seem to have died healthy, I would not do a huge water change, unless that is not inconvenient for you. I would test the water for ammonia, nitrite, and nitrate before you empty it out and refill. All three of these things can kill fish.

 

[j.w]

Very sorry to hear of your terrible loss of fish

 

[ReadLisaScott]

Thanks for all the input. Interesting idea about the fountain pump. I'll be sure to have a backup next year. Like I said, I have no idea how long the aerator wasn't working. Could've been weeks. the fish I've pulled out so far look perfectly healthy, so I suppose that's a good thing at least.

 

[Dave 54]

Tell me did you clean the bottom of the pond prior to winter cut back on dead vegitation and clean your filters?
Preperation prior to the winter period can and does save the lives of peoples goldfish and koi , otherwise you can condem them to an early death you really can .
Weve prepared our pond prior to winter for the last 5 years and had no losses

Dave

 

[Waterbug]

I grew up in Upstate NY and kept a pond there for about 10 years. One winter the pond froze to 4'. It's a weird thing, in the past 5 years I've noticed a big increase online of people being told to keep a hole in the ice, add heaters, etc. For the past 500 million years fish were able to survive without people chopping holes in the ice and running heaters. But thanks to the web the fish now need heaters. Where I lived we had many ponds that overwintered fish, frogs, etc. As long as the pond did freeze solid (which some did). I'll bet there were ponds around you that had fish pull thru without can gizmos.

It is true gas exchange problems can lead to die offs, especially in back yard ponds that have a lot of fish. But it's even more true that fish and frogs can be killed by cold water. Like us they can handle cold water for some period of time. Colder the water the less time they can survive. They really can't last long in 32F water. A week, a few weeks. But they can last a long time (few months) in 39F water. 39F water is the heaviest (densest) water. When ice covers a pond wind isn't able to stir up the water and the water can stratify even in a shallow pond. Very quickly the water at the bottom will be 39F and the temp will decrease the close to the surface with 32F water just under the ice. The heat coming out of the ground will help keep that water at the bottom near 39F and the fish alive. Running a pump, or chopping a hole can mess that up. If you mix the water in any way the fish have to tough out much colder water.

For the most part fish viewed thru the ice will be laying on the bottom.

The question should be what is the bigger risk? Gas problems or cold? That's kind of impossible to answer, but we can make some guesses. We have some pluses. Cold water = lower fish metabolism, less O2 needs, less uptake of harmful gases. Also lower bacteria metabolism so lower production of gases. Cold water holds O2 better and also converts more ammonia to ammonium. If you go into winter with a clean pond there is much less harmful gas production. Lots of uneaten food, poop, plants, algae and even keeping a hole in the ice may not be enough.

NY winters can be very cold...but the cold doesn't last. In Sweden, Alaska, yeah, ponds can stay iced over for months. That increases the risk of gas problems. But in NY I can't remember ponds staying iced over for much more than a month. That makes gas problems a much lower risk.

Heater, sure. If it actually keeps the water temp up. That takes a lot of electric. The heaters that just keep ice open don't change the water temp by any meaningful amount.

High stocked ponds are a different matter. They're going to have problem without serious management.

To me, for Upstate NY the bigger risk is cold water.

I don't think there is any reason at all to empty the pond. The bodies are just organic matter, like algae or anything else. There's no reason to think there's any kind of special killer bacteria in the pond due to the bodies.

 

[ReadLisaScott]

It was incredibly cold in upstate NY for a very long time this winter. The pond was iced over for months. (I'd say the aerator worked for 2/3 of the winter.) When we cut the hole in the ice, it was about 6 inches thick. I did clean the pond and prep it for winter. I've used the aerator for 4 winters, and for those winters, I didn't lose a fish, or maybe just 1. Although those winters were much more mild. I wouldn't say the pond is overstocked, but it's certainly more heavily stocked than a big natural pond. Maybe cold was the issue. I don't know. It's just so sad to be pulling all these dead bodies out. I really appreciate all the input and understanding. Most people don't get why it's so upsetting: "Just buy new fish" they say.