Pond Boss Forums MANAGING AN EXISTING POND Evaluating and adjusting fish populations June fish kill???

I'm Hoping someone can offer advice, we just realized our pond has had a massive fish kill. Everything is affected, from small bluegills to 3-4 pound bass. Grass carp and catfish are also dead.

We have done minimal management this year saving for a wedding, so we have not done any spraying and the duckweed is covering 90% of the pond. We have two aerators and they have been running fine.

This is the 3rd fish kill i heard of the last few days ,,, starting to get worried myself

DW is a real problem and takes DO out of the water by shading out plankton.

Even with aerators running it's still possible for DW to have that big an effect? Wow wouldn't have guessed that...

Any chance low DO was not the culprit? Just typing out loud here, but the aerators were running, and should've helped infuse some O2 into the water, and possibly kept an area around the boil open for sunlight penetration? Also, all sizes of fish seem to be affected, not just the larger specimens commonly seen when low DO is the culprit?

oops...sorry Dale, didn't mean to step on your toes...I type too slow!

That is weird. Killing all sizes of fish? I would think little 3 inch BG would not be effected that quick with air running?

Any chance something is getting into your water from somewhere? Or anoxic gas from the pond bottom is coming out?

I don't know have no idea just typing out loud like Spark. Sorry to hear that man.... Hope you figure it out. If you do let us know.

RC

DW needs to go into the list of commonly used acronyms.

It is, under "plant acronyms".

Oxygen is transferred to the pond water by the interface between the water and the atmosphere. Some O2 is transferred by the interface between the water and the aeration bubbles, but the majority comes from the atmosphere. That's one of the reasons why finer bubbles that are found in membrane diffusers are better for summer aeration - finer bubbles bring more water to the pond surface than bigger bubbles.

If the DW was covering 90% of the pond, then there might not be that large of an area from the diffuser boils that is in contact with the atmosphere, and not enough O2 was transferred to the water.

Then you have all the surface area of the pond that is covered by DW, and the resulting shade does not allow sunlight to the phytoplankton, which actually produces a LOT of dissolved O2 during the day via photosynthesis. When there is considerable shade, but especially at night, the bacteria, phytoplankton, algae and plants in the pond consume O2, along with the fish. Cloudy, windless days in ponds that have a high phytoplankton count (i.e. bloom) will also experience "summer kills", especially in the wee early morning hours due to an O2 crash. That's why it's important to watch the water clarity, and any BOW with less than 12" visibility due to a bloom runs the risk of a "summer kill".

In addition, a pond can have an aerator that produces bubbles, but not properly designed/sized for that BOW. So a pond could be "aerated" but it still won't help a lot in times of high oxygen demand.

The majority of the dead fish are located in the cove where water comes in. Our pond is fed primarily by runoff from a housing development a half mile away. We called the DNR and they think silt may be a contributing factor given recent rains. Maybe the DO was borderline because of the DW and the silt was too much?

We had already made plans made plans with the neighbor to create a silt pond next spring. The creek that feeds our pond used to be crossed by 4-wheeler and is now a 6 foot deep gully.

Here is a quote from esshup in 2012. Not sure if this helps or not but found it and thought I would share. Course this is him talking about a new pond so it may not relate?


Will it harden? Probably not. Will it hurt the pond? Not really, it'll just make it a bit shallower. That's why I dug my pond deeper than I wanted it, to plan for the future and it silting in. I'm glad that I did, I had 3' of dirt wash in when Hurricane Ike rolled thru the area not 3 weeks after I finished my pond. My 22' deep pond is now 18' - 19' deep.

It's important to have erosion control measures in place as soon as the soil work (i.e. digging) is completed.

If your soft soupy mess is mostly organics, with bottom aeration they will break down and be reduced in thickness over time. It's natures way to try and fill in all holes in the ground, be it a pond or a lake.


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3/4 to 1 1/4 ac pond LMB, SMB, PS, BG, RES, CC, YP, Bardello BG, (RBT & Blue Tilapia - seasonal).

Hello all. This is my first post, so apologies for any rookie mistakes I'm about to make.

My pond is also showing signs of an early fish kill. My crappies are gasping at the top and rolling on their sides. The scenario is this: 2 acre pond in south central Iowa, has reproducing populations of BG, LMB and black crappie (can't recall abbreviation at the moment). Also is 'old' pond, known to be at least 40 yrs old. Has ~ 43 surface acres, and ave 13 foot depth. Also has way too much FA, which I've been reading about here and formulating my plan to address it. Unfortunately, we've received almost 10 inches of rain in past 10 days, in 2-3 inch allotments. Happily, the inlets to the pond have small settling ponds with inlet dams and pipes, and the outflow is a ~ 4 foot corrugated metal pipe, all in working order. After the first huge rain, pond went up about 2 feet around the margins and then slowly receded over 2-3 days. The problem (in my rookie opinion) is the FA mats that were floated up and torn from their bases are now dying. The pond probably had 40% coverage of FA, but now broken up mats of FA are scattered diffusely. The FA dying off likely is causing loss of DO, yes? I am working on plan to reduce my sludge and nutrient load, and install an diffusion disk aeration system. It just takes time.

Probably not much to be done at this point, eh? Rake/net/drag off as much FA as I can reach and hope for sunny skies and some O2 production...

The rains have sure been a bugger, eh Luke? Our pond has used its emergency overflow twice this year.

In our case, the pond was built at least 5 years before we bought it, and the development had probably not been an issue at that time, they started phase 2 fairly recently. Big difference in water flow between a timber stream and a 60 home housing development. The DNR is planning on evaluating their water permit to make sure they are managing it appropriately

DrLuke, I think it could be possible your pond suffered a turnover with all the rain you've gotten. 40 years old and unaerated, there might be some nasty stuff down there.

Do you have someplace you can borrow a DO meter? IMHO Then you will know for sure if DO is the problem.

sprkplug: It very well could have turned over; we are seeing some nasty black looking water in areas.

Bill D: I agree, better to work off fact (if low DO is issue vs some other culprit). I don't know anyone off hand, but have been in contact with a local pond air supplier/installer, and may see if they could assist.

Kinda sad to see those nice fish kicking the bucket. We have been catching some really dandie black crappie (12-14 inches plus) and they looked really fat and sassy. I've only been the property owner since the end of May, but feel like I let them down/should have jumped on the FA better/sooner/faster. I've been reading like crazy, and really appreciate what Pond Boss forum does. Thanks to all you pros and regular Joes alike...

okay, I finally went back and looked it up. BCP=black crappie. I'm slow but I'm slow....

The FA probably did not cause the problem unless it is dying in large amounts or covers a large area.

So maybe a turnover as sprkplug suggested? Anything I can do in the short term? I'm gonna work on reducing the sludge and nutrient load, but as I've learned from reading many of the posts, it takes time and planning.

The FA is broken up badly, but small mats are probably covering 60 percent of the pond when it's still; when the wind blows, it packs it into the down wind corner(s)..

oops, double post

I am curious, has the DNR been out to your pond to see the kill and collect water samples?

If you have a tractor mounted bush hog style mower you can back the tractor close to the water, let the 3pt down where just the rear of the mower touches the water and the blades just touch the water. Operate the pto at mid to slow speed, enough so the blades do not flex all the time but still move the water.

It takes some playing with the speed of operation, the depth of the machine in the water, but a 3pt mower can act as an emergency aeration device. Set it so the throw of the blades cause a circulation of water in the pond. This will bring new water to the surface for the surface to air interface to allow DO to increase in the water.

Make sure the parking brake works and chock the wheels. If the tractor rolls into the pond it will be a bad deal. Make sure tractor does not over heat. Watch it.

Short term emergency solution only.

Commercial fish farms have pto aerators specifically for emergency aeration use.

Does that black water have an odor, or have you noticed a bad smell around the pond?