Hello Bob,
Thanks so much for the reply. I purchased a 100mL(3.38 oz) bottle of Duramycin 72-200 Antibiotic. It contains 200mg/mL of oxytetracycline. It is recommended for cattle and swine. I mixed half the bottle with half a bottle of Karo syrup and 25lbs of food and added it to the empty feeder and began feeding last night. I feed about 10lbs of feed a week and will mix and feed the second half when the first runs out.

I am not aerating and do not have a well to dilute. I didn't think I was pushing the envelope with 10lbs of feed per week on a 2 acre pond, but I've definitely done something to cause my first fish kill. Like I mentioned earlier, the only change in the past few years is the addition of lime this past winter. Aeration just isn't in the cards at this point.

Does it make sense to send off a water sample for analysis?

Thanks again for taking time to respond to my post.

Ray.