My neighbors pond had a fish kill over last few days. Aprox 100 floating bluegill and crappie.Very few bass. No small fish all over 6 inches. One crappie still alive had cloudy eyes. also bloody around dorsal fin and scales. He thinks its runoff from a sprayed bean field. I think its a localized decomposing growth and the fish were gassed and had no oxygen.

Need a lot more info to tell for sure.

Because fish less than 6" are not dying in mass then it is very likely NOT due to run off from the soybean field. When it is a toxin problem all sizes of fish will be dying and most often small ones will die first because they are more toxin sensitive than the larger fish. When its is a too low DO problem largest ones usually die first as in your example.

Often there is more than one stress factor present. When fish are severely stressed all it takes is a little more and they start dying. That is why water quality is so important as it helps keep stress down. Bill is right likely not runoff. That does not mean that water quality is not adversely effected by runoff. In my experience chem runoff is not often the actual cause of pond fish kills.

Several plant species start senescense or dying back this time of year. If they represent the bulk of plant biomass that is already high then stage set for low oxygen issues. Warm water and overcast skies can complicate issue. Low oxygen then can promote disease issues where infection involved they may not even be evident until after low oxygen event passes.

A bloody looking mucous sounds like Columnaris, which is bacteria that is always present. Stress allows it to become an infection with near total mortality rates on susceptible fish if left untreated. Potassium Permanganate is available, reasonably priced, and easy to use in large bodies of water. It will turn the pond a deep reddish purple and needs to be dosed accurately.

Treating is pretty useless however, if not discovering and correcting the original stressor that caused the outbreak.....

I have witnessed 3 ponds have fish kills - one was mine and other two were on deer leases I hunted on. Lost huge bass and catfish - all three were from turnover and lack of oxygen - it is very depressing

Thanks so much for the help. He was certain it was runoff and i was certain is wasn't. This will help save a confrontation.

Cloudy eyes are typically symptoms of burn.
Another possibility is drastic pH change due to photosynthesis and respiration. That occurs in ponds with low alkalinity and heavy plant mass.

We've seen a small number of kills here in the last several weeks. I attribute it to pond turnovers. The top several feet of our pond and small lake thermoclines are in the mid-80s. I haven't measured lower, but I'm guessing that below about 5'-6', the water is in the 60s. Every couple of days we've been getting 2-4 inch thunderstorm rainfalls with really high winds that drop our air temps from the mid-90s to the low-70s in a matter of minutes.

This article (East Coast Flash Flooding) will give you an idea of what the weather has been like recently where Todd3138, Sunil, and I live.

I was in Wisconsin this past week and my wife called to say that water was coming in around our chimney and bathroom vents -- through a new and expensive roof we had installed three years ago.

I'm not surprised we've had fish kills in our area.

I was in iron river a few weeks ago too.

Bobby -- I got back last night. What a time we had. We're all a lot older, so nobody even got drunk! Besides the cousins, lots of toddler-through-college friends and in-laws/out-laws from Brule, Iron River, Oulu, Orienta, Delta, Mason, etc., showed up at my cousin's place. We were so busy, I never actually made it into town. But many came from the Highway H side of town to the Oulu side of town to visit.

One of these days you and I may yet meet at the A&W!

Hullu poika,
Ken

That kind of weather is somewhat normal in NE Texas. I measured my surface temps down to 2 feet and it was 94 degrees. Several rain storms later within a couple weeks it was much cooler(I just did a stick my hand in for 2nd water test) guessing mid 80s. I wondered how this would effect my pond/fish. I did see two dead CNBG, before the rains, but that was it.

It depends on a couple of things. Your pond basically stratifies into three layers. The sun heats and helps oxygenate the top several feet. The bottom layer gets a lot less sun, so it is heavier, much cooler and has far less oxygen. Plants and fish usually can't live there. In between is a transition layer.

Strong winds cool rain can cause the pond layers to literally turn over. The temperature shock and change in oxygen can be lethal to fish, especially the larger fish.

Don't forget about the Hydrogen Sulfide that is also mixing in the water column from the anoxic bottom layer. If that is abundant enough, it can kill the fish even if there is enough O2 in the water, and it doesn't take much H2S at all to kill them.

If you have a lot of water run into the pond during a storm, and out during a heavy rain, the cold rain water will displace the hot surface water rapidly or insert itself in the layer that the fish normally are living. This new water can have drastically different chemistry then your normal pond water, which will also stress your fish.

I have seen the evidence twice this summer when heavy rains created a very muddy inflow. Looking at the pond right after the storm, the water appeared clear until I noticed a very well-defined muddly water layer on the bottom 5 feet down. A day later all of the water was muddy once it mixed in the wind.

I would suspect that if you have a rain and hail storm, that inflow water can be cold enough to drive the anaerobic layer up from the bottom and do some crazy things to the bacteria down there by inserting oxygen. Who knows what, but the fish probably don't enjoy that.

Thank you Scott. My tired old lazy brain couldn't remember the term Hydrogen Sulfide so I skipped it when I wrote that.

Anybody who has walked around in the muck of a pond or swamp, and got the rotten egg smell, has experienced the effects of H2S.

Rapid temp changes can kill fish and/or increase stress. That together with existing stressors can add up resulting in dead fish. In most cases however the temp changes need to be at the lower or upper lethal limits. That is usually not at 60-80 F temps. Rapid changes in the 95+ or below 45 range can easily kill common southern pond fish. A common DO turnover event in summer (thermocline reversal)is a cloudy day or two with a heavy T-storm (cold rain).

Hydrogen sulfide is H2S, a toxic gas with a "rotten egg" smell. H2SO4 is sulfuric acid, also known as battery acid, and an entirely different chemical.

John, thank you for the correction, I changed my post.

Here is a link to fact sheets on many water quality items.

https://srac.tamu.edu/viewCategory/25