Pond Boss Forums GENERAL QUESTIONS Help Copper Sulfate Killed My fish?

Hi all.
New to these forums. We just got some land with a pond on it. Luckily, the previous owners agreed to still maintain the pond... When we got there today (after about 3 days of heavy rain), almost all the fish in our lake were dead. They put copper sulfate in the pond about 2 weeks ago. Is there anyway that the sulfate or rain would have killed them? They definitely died within the last 3 days, we are sure of that. All help appreciated
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Copper sulfate is used to kill filamentous algae, which is the slimy green stuff you have growing around the edge of the pond in the second pic. The standard recommendation is, if a pond has a good deal of FA growing, not to treat the entire pond at once because what happened to your pond can be the result. Dying weeds take up oxygen; probably the pond had a lot of FA and the previous owner got a little slap-happy or impatient or just didn't adequately research the application of the chemical. It's a shame too - looks like the pond had some nice-sized bluegill in it.

Welcome to the forum Chance9888!

As Walt said, copper sulfate can kill fish either through depletion of dissolved oxygen through the dying filamentous algae it killed or through simple poisoning if used in too high a dosage. How is your pond fed? Spring, run off, etc? The fact that you had a heavy rain a few days ago has me intrigued. Sometimes fish kills can also occur due to outside contaminants washed in during a heavy rain.

Irregardless of how your fish kill occurred, what is done is done. It is a shame none the less though. Now is the time to evaluate what you have left and move on. Many members on here have experienced fish kills and I am sure they will share their experiences of what they did and how to bring your pond back to life.

Best of luck and welcome to the forum again...

This fish kill can be summarized as follows:
1) Excess aquatic plants peripherally and heavy plankton bloom in the water column.
2) Someone treated the vegetation, it started to die and decompose, dramatically increasing the BOD (Oxygen demand).
3) The plankton bloom crashed (died) at the same time as the plants were decomposing. The plankton bloom crash was either a result of copper sulfate treatment or it ran its course and was finished off by the heavy rain.
4) The resulting oxygen demand suffocated your fish. You can tell the fish suffocated because many of them have their mouths wide open, jaws locked and gills flared open.
5) The copper sulfate did not directly cause the fish kill. Decaying vegetation caused it. The copper sulfate was the stimulus. It did what it is supposed to do...kill the algae and plankton.
6) There's good news here, though. Your fish kill was probably partial and the pond will recover.

Chance, welcome to Pond Boss, we're glad you found us. I'm sorry it's sad circumstances that let you to post here for the first time. But the good news is that you found the greatest resource for pond management on the blue planet and you've heard from THE pond boss himself in your very first post (very few folks can say that). With this crew you'll be able to get your pond back in order and probably better than it ever was.

If it were my pond I'd begin the rebuilding process by learning all you can about pond management. Bob Lusk has written several great books about pond management including "Perfect Pond Want One?" and "Raising Trophy Bass" which is chock full of information even if you don't want trophy bass. Another book in my library is "Water, Weeds and Algae". These are all available through the Pond Boss Store. Also subscribing to the magazine is a good idea as well and a sign of superior intelligence.

Interesting, I had never heard that before. See there I've already learned one new thing today.

That makes sense. That's the way they always look when I leave them in well water in the fridge overnight before cleaning.

No correlation Theo. Your fridge fish look that way because they have suddenly developed an irrational desire to consume large quantities of DMD.

Is it possible there was a turn over due to the heavy rain also? It's pretty hot down there and a heavy rain in the 70's could drastically drop the water temps causing a turn over couldn't it? I.e. 90 degree surface temps and 70 degree heavy rain is a 30 degree drop of temperature and could initiate mixing?

Chance,

Welcome to the Pond Boss forum. Sorry about your fish kill. How deep is your pond?

Cecil,
Sure, it could. But, with that black water and floating algae mixed with dead plankton ringing the surface, it would take more than just thermal mixing to kill all that greenery. A turnover wouldn't have killed the peripheral plant life.

I agree with Bob's assessment and Cecil could also be right that the cold rain added to the DO reduction.

However let me add one more to the mix. CuSO4 in low alkalinity water can and does kill fish even in low amounts. The combo acts to inhibit gill function and the fish can't breath. The fish gills work but they can't uptake O2.

http://www.pondboss.com/forums/ubbthread...=true#Post35566

Oh I wasn't discounting that at all. Just thought since a turn over was not mentioned it could have been one of those all of the above situations. Ewest even added another one that could have been added to all of the above.

Didn't someone here once say that fish kills could be due to more than one factor at once? Was that you Bob?