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