Pond Boss Forums GENERAL QUESTIONS Help Fish Kill Possibly Due to Starting Aeration

I just had a fish kill possibly caused by starting aeration in hot weather. My pond is about 1/4 acre near Burleson, TX, south of Fort Worth. The pond is 10 feet deep in an oval shape with 30 degree slope on the sides. It was stocked with about 170 18" CC, 50 CNB, 10 LMB, and an unknown number of FHM.

They seemed to be doing fine with the coming on of the more normal high 90s to 100 degree weather and I had only had small numbers of fish die before with 3-5 after heavy rains (Maybe something in the runoff from my rural neighborhood?). Another change that had occured with the hot weather was a dieoff of the pond weeds on the shore and about half of what was in the water.

I had not been aerating and had not seen any signs of fish in distress but deciced to start aerating a couple of days ago. The first time I let the pump run for a couple of hours in the afternoon. This time I turned it on yesterday afternoon and left it on and did not get back to the pond until 8 this evening and it was still light enough for me to see a bunch of white bellys on the surface. I used a rake and pulled as many out as I could reach before it got too dark.

I did not see any live fish in distress. There were about 30 dead fish were all large CC and two 12" LMB that I had not seen since I put them in 2 years ago.

The only change I had made is aeration. I shut off the aeration pump 30 minutes ago on my walk back up to the house to make this post. I wellcome and would appreciate your advice on what to do next.

Also, what instrument is used for testing disolved oxygen?

Thanks,

Richard

I'm no aeration expert, but the die-off of aquatic vegetation is a huge red flag. Big time withdrawal on your oxygen bank account from the dying plants. Then the aerator kicks on and brings your very worst water off the bottom and mixes it into an already low DO system. I believe that's why they say to start up the aerators earlier in the year and let 'em run.

Thanks Bruce,

I just went out with a light and took a look at the water and it is just an ugly mess. I turned the aerator back on because I'm guessing there would only be less oxygen in the water if I left it off.

I pulled out all the dead fish I could reach and put them out in the open where I hope the neighborhood buzzards will see them and come in for breakfast and clean up most of it so that I will not have to bury it. At this point I would even welcome blue herons.

I didn't see any fish in distress unless they are all toast and just haven't floated yet.

Any suggestions for adding bacteria or chemicals to clean it up? Maybe get another aeration pump?

Thanks,

Richard

Get as many dead fish out as you can. More will probably float up tomorrow, and the next day, and the next....

I'm not knowledgeable when it comes to aeration issues, but I've seen my share of bad water. I think since you're in Texas you need a serious game plan for 2008, and just try to get through the next few weeks. I don't know if there's a magic bullet for you. Do you expect enough runoff over the next couple of months to replace your water?

If the weather resumes it's way above average rainfall the chances of water replacement are good. This last month has been the first really dry break and temperatures up until this month had been mild. The heavy spring rains have had it filled to the top and overflowing almost every month this year.

I think in your case, water replacement is a good thing. If you were to get more rains soon, it could cause the death of some of the fish you have left, but ultimately it sounds like you could use a fresh start---and a good long term aeration plan. I hope one of the experts chimes in to get you some specific recommendations. PM one of the experts to get a quote on a specific system.

One other thing I need to do is to drag all of the dieing vegetation out since that looks like one of the dominoes that lead to this situation. It was pond weeds that came in on the wind, as I have seen them on other ponds in my neighborhood. They added cover for the fish so I left them in but eventually they were covering 20 % of the surface area so I started raking some of them out. Then the hot weather came in and started killing them and that probably led to this. They will have to go and not be allowed back.

It's time for me to hit the sack so I can get up early and rake pond weeds and casualties. I hope the buzzards have an early breakfast.

Thanks for your advice Bruce.

Richard

Richard, sorry about the situation, several recent posts about fish kills you should read.680 CC per acre in your situation may be too many too soon. Running your aeration probably lowerd you DO not increased it. Your oxygen bank in an unaerated pond in warm water is primarily in the top few inches so pumping too much lower water to the surface only dilutes the O2 level. This is one of the reasons for starting slow. The standard startup procedure is 15 minutes to start and double it everyay and on day 8 and you are running 24/7 PROVIDED you observe nothing negative in that time frame.You need to know your pump and diffuser capacity to calculate how your aerator is sized, it may be too large or too small for your goal.

What is the instrument used to measuere DO and where can I get one?