I�ve been a long time lurker, I have usually been able to find out what I needed to know by reading old discussions. I finally decided to become a member because I am currently experiencing a devastating fish kill event and would like to get some advice. I have a .75 to 1 acre pond that is probably at least 30 years old. I�ve lived here for 18 years and the pond was already well established, healthy, and full of bass and bluegill. I�ve managed it primarily for trophy bass during my ownership and it has been fantastic � my pride and joy, loved by my family and friends and our primary source of fishing recreation.
Overnight Wednesday morning 06/26/2019 we woke up to hundreds, likely even thousands, of dead fish. Everything seemed fine the evening before, I was actually walking around the pond that evening appreciating that the water was starting to clear up from the recent heavy rains and watching the fish swim around. I talked to our district�s DNR fish biologist about my situation and he seems pretty convinced that this is a water turnover event caused by the heavy rainfall. I think it is due to runoff from my neighboring farmers field or some other type of contamination. The farmer just sprayed his field with liquid manure (and maybe something else) days before this last large rainfall and I believe that is what has led to this large fish kill event. I�ve experienced minor fish kills over the years with this pond, but nothing has been like this � something is different about this time, but I�m not sure how to determine and what to do about it. The weather is not my neighbors fault, but I feel stuck with a bad situation.
I�ve been thinking about adding an aeration system to my pond for years, but the expense has always simply been too large for our budget to handle. This fish kill is looking like it�s going to totally wipe out my fish population at this point, so I think it�s time to make an aeration system work somehow � unfortunately too late to save my fish. From my understanding of pond construction, I really shouldn�t need aeration � my pond is constructed just right for its intended usage � fish. Most of the pond is about 5-6ft deep with the deepest area being about 8-10ft deep. By my understanding, the shallow construction should prevent stratification and large turnover events � it has certainly worked well to this point. It is also my understanding that aeration is less effective in shallow ponds like mine. Further, I�ve read that aeration can actually cause turnover and fish kills since the purpose of aeration is to circulate the water and prevent stratification. Those are additional reasons that I have put it off as not necessarily that important for my pond.
We spent all evening yesterday removing as many of the dead fish as we could. We nearly filled the dump bed on my ATV and this morning there were nearly just as many more. Do you think this is just the first time in 18 years that my pond has experienced this extreme of a turnover event and that is the likely cause? We have had plenty of similar large rainfall events over the years and not had this happen. Previous fish kills that were obviously from low dissolved oxygen events primarily effected only a few of the large fish while this event is effecting everything � all types of fish of all sizes. Do you think my best reaction is to get an aeration system installed as soon as possible? I am a design engineer by trade, so I will likely piece together my own system to save money. Any other recommendations or observations?
If the DNR guy thinks it was turnover then he is likely correct. That does happen in summer upon big/cold rain events occurring in a warm pond envior. The more fish in the pond (carrying capacity reached) the more likely that low DOs will effect the pond as BOD is greater.
What did the water look like (color and visibility) before the rain and after the fish kill ?
I just had the same thing happen to me about two weeks ago. My pond is 1/2 acre and a little over 30 years old. After one of our recent heavy downpours. It took me three days to remove all the dead fish. In total about 30 gallons of fish. My water went from clear to less than 8 inches of visiblity with a lot of black globs floating. I do not have a farm runoff. I do aerate but have only been 8 hrs a night with one diffuser. I will be installing a second one shortly to keep it mixed up. I have not seen any signs of survivors. Only tadpoles. I have set out a fish trap but have not caught anything yet. This weekend I will search for signs of life. I might take this opportunity to go from BG and LM to YP and SMB.
See if you can find out what the farmer sprayed, a significant rain and run off event coming into the pond after spraying might have been the culprit or a contributing factor. The only way to know for sure is to ask, it's a good idea to have any open line of communication with your nieghbor farming about what chemicals are being used that may end up in your pond, it might help prevent future problems.
Although your pond is shallow I'd be surprised if it didn't stratify anyway. When you stick your arm in, is there a level where the water temperature quickly gets noticeably colder?
What did the water look like (color and visibility) before the rain and after the fish kill ?
The water was surprisingly clear before this latest rain that seems to have triggered this. Normally this time of year I would be fighting a fairly significant filamentous algae bloom, but there was none. We've had a rough spring around here with record rainfall, but we had a small break a couple weeks back and that gave the wter time to settle and clear up. I figured that was why the FA had not taken hold like normal. The water turned muddy after all the rainfall, but still no algae. The night before the fish started dying the water was starting to settle down again and I could see the fish in the water down to a couple feet deep.
I know the farmer had just sprayed liquid manure (hog poop I believe) just days before this last rain. We had a river probably 30 feet wide and 2 feet deep running into our pond from his field during that rain.
I am now getting a bloom of what I think is blue-green algae, which is not normal for my pond. I had swirly patches of green "scum" floating on the pond last night along with several hundred more dead fish.
We had a river probably 30 feet wide and 2 feet deep running into our pond from his field during that rain.
That's A LOT of inflow water for such a small BOW. I bet your pond water was flushed/turned several times. This has to have changed ALL the parameters in a short period...temperature and water chemistry flip flop. I have read that rainfall carries plenty of DO, but the rest of the parameters changed quickly stressing the fish and without aeration to keep the water column consistent with DO, even the available oxygen content changed.
Right, wrong, or indifferent: that's why I added aeration to my pond as it has excessive watershed. A massive inflow can be "settled down" some because all the water in the pond would have consistent properties and would not add to the "flip flop" with it's lower toxic waters. So far so good, but 30 feet wide and 2 feet deep sounds like a small river.
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