hole in ice all winter, 95% of the fish are dead as ice melts

[waynefrcan]

Addy since you have been at the pond to see it all first hand, there is nothing that I can add that will be any better to help.

Ok read all the posts here. How many yrs has he been running the same pond setup? Maybe the aerator at 18" is too high for 6.5 ft pond aeration.

 

[brokensword]

addy, did some more research and happened on the thread below. It comes from a forum of ponders who are interested in game/commercial fishes, but seems their problem/solution might be of benefit. Basically, if you read through all three pages, the basic idea is

IF you aerate, do so NOT at the deepest depth but at about the halfway point.

If you don't aerate, keep the snow off the ice so light can get in and the natural plants can give off O2.

Supercooling seems to occur in shallower ponds being aerated too heavily or where there is too much water movement.

And, the point that might pertain here especially;

IF you aerate, don't OVER AERATE. A small hole is sufficient and the over aeration makes the water at the bottom too cold, which leads to all sorts of problems that help cause winter fish kill, mainly by using up available oxygen.


So, maybe what happened here is that your neighbor over aerated and that's how the oxygen came to be below fish-sustainable thresholds. I'll post the link and any interested parties can read and critique. These folks came at it from both a commercial as well as academic position, so I'm inclined to believe there's more than a dollop of credibility.

http://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=50723&page=1



If I can, the very last post sort of sums up what I tried to relay above. I didn't get permission to use the quote, but I'm linking to the original, which IS public. I'm only trying to save time/effort for those that don't have the time or inclination to read through all three pages. If this is not permissible, delete as you see fit. I'll quote the post below, directly as they are his words, not mine.


"I believe Cecil has your answer as to what may have gone wrong.Winter aeration can be quite simple and complicated at the same time. When trying to find and maintain the balance of a high percentage of DO saturation and water temps not stressful or lethal to fish without a DO meter it is difficult.I find most winter aeration overdone in the midwest.When your BOD is very high winter aeration is more critical and with a low BOD it may not be needed at all.When in doubt and no way to tell the DO level just keep the snow off of at least 20% of the surface and chances are you will be fine. This is my preferred method. Next method is to have a seperate diffuser (or move your exsisting one) to the shallows and only run when snow cover is present and only as long as it takes to melt off an open area and them let refreeze clear.On ponds where multiple diffusers are present shutting down the majority of them and using one designated as the winter diffuser works too. Caution if you have more CFM going to that one diffuser than it can handle.Either vent off so that you have 1-2 PSI going to that diffuser or install a diffuser that can handle variable CFM (look at the AirPod from Aeration Technologies Inc) as it can take from .5 to 10 CFM.Lastly if you have your only diffuser in the deeper part of the pond and cant move it and cant install a seperate winter diffuser then consider at least venting off most of the air to it, say 1-2 PSI and slow it down. The idea of large open water so a pond can gass off often supercools the bottom of small ponds (8-10 acres and less) and does more harm than good.Winter is already the tough time for fish and over circulation only makes things worse.Most 40F water that is 80-90 % saturated has 10-12 ppm DO in it already and that is twice as much O2 as you need this time of year.Many of todays diffusers can circulate over 4000 GPM with only 1 cfm (20 ft of water)and your pump may have over 4 cfm available.Since proper winter aeration differs so much from year to year I would stay on the conservative side in a small pond.If you have 20 ft or less depth in a 1 acre pond and have open water all winter from aeration and air temps single digits and below you probably have your bottom water too cold (less than 39F) If you have one or two diffusers (depending on depth) running in a 8-10 acre pond all winter probably will not cause any problems as its the smaller ponds that are the most difficult to manage.Use the ice to your advanage as insulation against the super cold temps. Good Luck."


Ted Lea




And if linking to that other thread is in error, let me know. I tried to sum up what I read but maybe I did so with biased eyes. There's a lot of reading and more than a bit of in depth analysis to go along with ordinary chatter/experiences. I found it worthwhile and believe much of what was written.


Michael

 

[addy1]

Thank you Brokensword/ aka Michael! What you say above in all your posts makes the most sense. The fish were hanging in there with thaw, pond open, pond shut during the winter. We did get snow, but it usually did not stay long, it would melt off the pond ice in a few days.
it is fine to quote from other places and add links.

In February we had two storms of heavy snow, colder temps, i.e. down into the minus 7 degrees. The pond froze over everywhere except where the air was bubbling. That is when his fish started to die off. He was going by the don't put the aerator in the deep area of the pond, messes with the layering of the water temps. So he put it into the shallow end, high flow. He had maybe 100-150 plus minus fish, around 13k gallons (around) as they say, average of 5 inches counting fry to grown ones.....................his pond is bigger than mine. The smaller pond was 1200 gallons, with around 10-20 fish. I don't remember all the numbers he has fed me. That pond had slower air flow, a T off the big aerator, it did freeze deeper, being a smaller pond.

pondmaster ap100:
Linear Air Flow Volume - 3.6 CFM
Maximum working water depth - 11.5 ft.
Power consumption -- 104 Watts
Chord Length 6 ft.
Quiet operation--Noise Level ..45dba (very quiet)

He had the majority of the flow in the big pond, with a T running to the small pond.

He has run the same setup for the past 5 years, but this winter for us and everybody has been darn cold and long.

Not a ton of junk on the bottom, some late blown in leaves, a little amount of muck.

I am going to suggest to him those pond breathers, somebody is using up there in canada, need to find out who it was, maybe it is mitch.
http://www.amazon.com/8PB-Breather-Heated-Aerator-Watts/dp/B000HHM9U0

I am also going to suggest a good cleaning of the pond, maybe use that stuff someone suggested,sodium percarbonate is the main ingredient.

 

[brokensword]

addy,

it does seem odd, since the weather you get is less severe than the ponds in question (most of them, if I remember correctly) in the 'other pond forum thread'. They were talking over 30" of ice! And THEY would often NOT aerate, with fish that are probably not as cold hardy as gf, too. So you'd think your neighbor's setup would have been a walk in the park compared to the ones I read about. But somehow, I do think they suffocated and a lack of O2 is responsible. Considering how cold our winter has been here in Mi, with lots of record below zero temps and the most snowfall I've ever seen, I'm more worried now about my own fish. Still covered so I can't even guess. Hopefully, I won't have the same thing happen to me.

Michael

 

[addy1]

I can not think of any other reason for them to be dead. Any poisons the frogs, snails etc would be gone too.
So going to approach it as a o2 kill, we did drop way cold during the last part of february way cold for us.

He has recovered and will clean, restock, low levels and just see what happens next winter. He likes the pond breather idea.

 

[dieselplower]

Whoa now what has been decided here? It seems like the article from the pros points to too much aeration causing the bottom of the pond to get too cold.

 

[addy1]

opps sorry, doing our taxes................meant too cold. Brain overload.

Whoa now what has been decided here? It seems like the article from the pros points to too much aeration causing the bottom of the pond to get too cold.

 

[dieselplower]

opps sorry, doing our taxes................meant too cold. Brain overload.

Don't get me wrong... I'm not one who would feel I know enough to say what happened. Just wondering. I have said before that I did not like the method if using aeration to keep a hole open because it introduces very cold air into the pond, below freezing. Of course I want to say I was right because it would give some validity to my previous claims. I just really want the correct info to come out, whether I am right or wrong, so it can be avoided in the future.

 

[Catfishnut]

Addy,

I believe that we are investigating this through the wrong approach. I am a troubleshooter by trade (in electronics) but there is an art to troubleshooting that goes along with any subject be it electronics, chemistry, physics or physiology. Our post mortum research project here is the death of a large population of fish.

So far, the discussion has focused on causes of death for these fish. However, we have a control group in our lab today... The surviving fish. So our question should be: Why did these fish live? Is there something unique about these fish that the other fish didn't posess?

That fairly well rules out toxins. Any toxin lethal enough to kill that many fish in two separate ponds should have killed all.

The probability that the water temp got too cold is low. All the pond and all the fish were subjected to cold temps in the two months prior and did not suffer any as far as we know.. Cannot rule this out, but it seems unlikely with the facts presented.

The water quality has been tested and found to be acceptable, but this test was performed post facto of the death of the fish, so we cannot rule water quality out at this time.

I would not expect ammonia or other natural toxins from the fish or the detritus because they would have been perishing long before if that were the case. The water temp and feeding regemine should have kept that to an absolute minimum and since there was an open hole in the ice all winter these gases should have been escaping.

What other clues do we have? If I read one of your statements correctly, it seemed that the larger, older fish and the younger, smaller fish were most affected (but some in between were also). If there was a survey by the pond owner regarding size/age of the fish which perished compared to the fish which lived, we might be able to identify a specific line of questioning to isolate the cause based on that if there is any pattern to it. If the pattern is random, it may not assist.

A question I would ask is were all the dead fish found in any specific location? Were they by any electrical device within the pond? Or just randomly scattered? With the one more recent thaw in the ice, could they have moved to a more shallow location and got caught there when the temp dropped too quickly?

Personally, at this point with everything you have submitted for us to read regarding the situation, I want to say that it was either a fish disease or a lack of oxygen. If my assumption that the middle group (median age and size) were the most able to survive, then lack of O2 or a disease would be plausible.

I resist the notion about disease, because of the water temperature. I wouldn't think that diseases caused by virus' or bacteria would be prevalent at these water temps.

It certainly is a mystery and I hope they are able to isolate the cause and prevent it from reoccurring.

Gordy

 

[callingcolleen1]

Put away the test kits people, they will not tell you what happened THEN, and this is NOW! Oxygen was mostly very low and gas bubbles built up killing the fish. Test kits will not tell you what happened then, and the gas bubbles are mostly gone with the ice melt. I never use test kits, EVER not in the last twenty years of ponding it. I look at my fish and I can tell what they need most of the time. If they are low of oxygen in the summer, they will not swim fast. If they have lots of oxygen they swim very fast. Look at the fins, are the clamped up, or do they look stressed. That is a BIG problem when you cannot see under that thick of ice. Bubblers suck when weather gets cold for long periods of time and I have seen many friends loose all there fish in one season due to wintering with just a bubbler. Some people can get away with a bubbler but for most of people I know here in this town, they fail to provide a good home for fish in extreme weather conditions.

Ice cold water DOES NOT kill healthy fish, or my fish would be dead, as I only use one heater for all three big connecting ponds, and I still get lots of ice. The bottom pond was totally iced over and I had a foot of ice, but the water was always flowing between ponds. Water temperature remains barely above freezing in my pond for most of the winter, despite the heater.

You can rule out sickness as fish do not catch a cold or get summer time flu or worms ect. Goldfish and Koi are Coldwater fish and they do very well in the cold water, it keeps them fresh and free of sickness. In all the twenty some years of wintering my ponds, fish never get sick in winter, just does not happen. If there was a sickly fish in the summer, it may not make it thru a hard winter, but for the most part, sickness can be ruled out. However, if the fish were moved just before the cold weather, stress and injury to fins and scales may turn to fungus over the winter and that could kill THAT fish in extreme cases, but would not kill off 95% of the fish.

The problem is always the same, they fish simply ran out of oxygen and sucked in too much gas most likely. That is why 99.9% of mass fish die offs occurs in winter, and for that reason alone.... unless the pond was very shallow and they froze IN the ice.

I choose to keep the ponds flowing as flowing water best rids the pond of built up gases, and will melt the ice faster. You can get away with a bubbler some of the time, but bubblers do not clean and filter the water and in some cases can just churn up the bottom and make water quality bad. Bubblers freeze over quite often.

If your pond is three feet deep and the first foot of ice freezes, your pond is now only two feet deep at the deepest part, so lots of water volume is lost. Sustained cold weather with no heater creates more ice over time. How deep was his pond and how thick was his ice?

 

[callingcolleen1]

I highly doubt that any fish are left alive, if 95% are dead, the other are most likely dead too.

 

[Catfishnut]

Colleen,

I am in agreement, of course, that it was a lack of O2. The strongest fish survived, the older and larger fish couldn't get enough O2 and the younger smaller fish were just too weak to deal with it.

However, if your and my assumptions are correct, why did this not happen earlier in the midst of the harsher part of winter?
What changed?

I have this one idea rolling around in my head, but it may sound implausible. Can a small pond do a "turnover" like a natural lake does in the spring? If the temperature of the surrounding air and the radiation from the sunlight were sufficient to cause the water to turn over from top to bottom during one quick warm period and then a cold snap hit and left the warmer water where the fish were hanging out with less oxygen, they could have been deprived of O2 for a few days until the balance was restored.

I don't know if something like this would be possible. I would think that it would be well known if it was a common occurence. I cannot see it going unnoticed otherwise.

Gordy

 

[brokensword]

Diesel; it's not the fact O2 was used, it was where the supply is being placed. All the 'pros' in that other thread were of the opinion that putting the air supply at the deep end wasn't a good idea. I've heard that here as well as other places, so no surprise to me. They DID say that keeping a hole open helped (just not large, open spaces of water), as well as or optionally removing the snow on top of the ice so light can get in and help the submerged vegetation produce O2. They also said they tested and with 5" of snow, almost all light was blocked. Without the light, the plants can't do their thing. (small fish load won't matter, large fish load will consume available O2, as well as a large load of decaying plant material will consume it as well, plus give off the toxic gasses). With a hole open and oxygen supplied, it's giving the fish what they need, if they need it. Thing is, can't pull the 'warmer' water at the bottom and mix it with the top. The warmer water is where the fish gravitate to. I just wondered if addy's friend had the air supply deep enough so there WAS some mixing going on. Hard to say as I don't know how deep it really was, and if it was a problem in the first place.

None of these pros used pumps to move water (but then, they are using basically small lakes to keep their game/food fish), that many did nothing. But they have deeper depths to work with where stratification occurs and the water stays closer to 39 degrees. With a smaller pond, from what I read, this stratification isn't always there (if at all; a study I read says 6' depth is necessary for this to happen). This neighbor's pond was deeper though, I think addy said 6.5', so the temps should have been okay for normally sustaining the fish. The main idea I got from the other thread is when you put TOO MUCH air in and needlessly lower the water temp where the fish are.

Colleen, you've had success with what you do, but I don't think your fish would make it without your heaters. Without them, the moving water would not do much (from what I read, the beneficial bacteria is dormant or negligible at these temps) and all you'd do is move warmer water into colder. As long as it kept above freezing though, should be no problem. But I'm unsure if you get any gas exchange with having your pump always on--perhaps you do and that's a pump's benefit. I'm in the camp that if you can let the gasses escape without building up (poisoning the fish /suffocating the fish) then they'll survive. The larger the fish/decaying plant load, the more often this has to occur. Adding oxygen, at the proper depth, will help with snow-over-ice ponds. Not sure exactly how low the aerator should be but according to the pros on the mentioned thread, no further than half way (and I think this is for deeper ponds, with 3' being mentioned as the target to hit there). If addy's friend had the aerator too near the surface, not sure that would hurt. If too much air, maybe there was too much mixing and the water temp lowered too far. From above:

"The idea of large open water so a pond can gass off often supercools the bottom of small ponds (8-10 acres and less) and does more harm than good.Winter is already the tough time for fish and over circulation only makes things worse."

And our ponds are typically measured in gallons, not acres. I'd say a small hole, some air, no deep aeration in the winter, and if you can, remove some snow to let the light in should work.

Gordy; how long would this turnover take to happen? Seems that the temps of bodies of water don't change that drastically. Is there a timetable for this, temperature/time dependent? Certainly would make sense if it happened as you suggest. Still, wouldn't the fish migrate up and down according to their needs? Does this turnover happen that fast that the fish can't compensate? Seems I've read here that those that use heaters often see their fish hanging out near it, in the winter. But I can still understand being immersed in O2-lacking water too quickly as a stress that ultimately hurts the fish.

Michael

 

[addy1]

Wow while doing taxes you guys were trying to figure this out, thanks for all the above information.

Tom's fish were in the pond for the last 5 years, obviously some were fry, 1 yr, etc old. He has not added a fish for a few years now. No feeding done, pond not touched during this winter. We only had spells of snow sticking on the ground, leaving the ice covered up. The longest about 2 weeks. The hole always open.
Here our snow falls and usually melts pretty fast, the snow that fell monday is almost totally gone already, that was around 8 inches worth.

The fish were everywhere in the pond, shallow, deep, floating, bottom. No collection at any point. The aerator was around a 18 inches under the water, in the 3 foot area. The deep end starts around 7 feet from where the aerator was. (it slopes rapidly down)

No electricity going into the water.

He still has around 6 fish swimming around a few tiny ones like two inches, then a few 4 inches or so and a few in the 6-7 inch range. Very healthy looking swimming well.

Now something I just thought of, his line from the aerator, 3/4 inch ran out from the pump around 15 feet if not more, that line would have been laying under the snow that fell before it dipped into the pond. Would that also have super cooled the air, but snow does insulate too.

His smaller pond, the air line was maybe 3 inches under the water, just a slight bubble of air. That one might have done a freeze over, he is not sure.

 

[callingcolleen1]

Winter is strange, and strange things can happen to pond and fish. I do not think a bubbler is good for extreme weather.
Catnutfish, lots of different reason for why it can happened later. First, the thickness of ice can be deceiving, you may think you only have a inch or so of ice, but near the shallow areas where the ground is frozen very hard, ice can be in excess of one foot I have discovered. Your once big pond can have less than half the actual volume of water it would normally, as water is displaced and turned to ice. Also, even though there is one air hole, it just is not enough in lots of cases. Gases can still get trapped in large pockets under the ice.
Second, it may have been the coldest part of the winter, but if the ground is only half froze, then that makes a big difference on how much ice you will get and how thick. If you have a long cold winter with sustained low temps for longer periods of time, the ground will freeze very deep. The deeper your ground freezes, the thicker the ice will be on your pond. If your ground is frozen three feet, then the ice on your pond will be three feet deep too!. Sometimes you just have to break the wallet and fork over the money and plug in the pond heater. His fish were slowly dieing off and he probably did not notice it with only one hole open in the thick ice. The area of town you are in may be more exposed to harsher wind and deeper cold. My ponds are between two houses, and the warmth from the houses may keep the ground by my pond from freezing as hard. Some ponds are just more exposed to the elements and without heat things can go wrong big time!
I feel bad the guy lost his fish, but I can't tell you how many people I know here that lost fish many winters thinking they would be just fine cause the had just the bubbler. I tried to tell them I did not think that would be sufficient for their ponds.
Then there is the "local Koi Guy" in town, and he has a ten foot deep hole in the ground pond, and he just used a bubbler cause he thought the depth of the pond would be enough. Last year he made out just OK, but this year was twice as cold for twice as long here in town. Last I talked with him, he said he was worried about his fish, and his pond water does not look good either. Some years the ground here can freeze very deep in some areas more exposed to harsher winter elements, I shall speak with him again as see what happened. He had some really big expensive koi in his pond.