Last Saturday when I threw out fish food the bream churned the water like a school of piranha feeding on fresh meat. They quickly ate the three pounds of food I threw out and probably would have eaten more if I had given them any more. That was the usual activity level.
On Sunday afternoon when I threw out a can of food, there was almost no activity. It was very hot and the sun was bright, and I hoped that was the problem. The pond had dropped about 4 inches in the past few weeks since there had been no rain, but there was still a good flow of water coming into the pond.
Monday afternoon as I drove down to the pond several buzzards flew off. I got a sick feeling in my stomach, and it was confirmed when I caught sight of dead fish floating around the edge of the pond. I walked around the pond and counted 107 dead fish - mostly big bluegill.
Tuesday morning I called the DNR fisheries biologist that covers Spalding County and he told me I was the third call that morning about a fish kill in local ponds. The hot, dry weather had left many ponds with low oxygen content, and based on what I told him, lack of oxygen was probably what killed my fish.
Fertile ponds have a lot of algae in them, that is what gives the water the green color. Algae is good - it produces food for the fish at the lower end of the food chain and during the day it adds oxygen to the water.
Unfortunately, at night the algae actually uses oxygen, and if it dies the decay process also uses up oxygen. If a green pond suddenly turns brown, it probably means the algae has died and the fish will be in trouble.
The water in my pond cleared up a lot Monday, but that was probably from the heavy rain Sunday night. That could also have been part of the problem The biologist I talked with said the fish could have been stressed because of low oxygen levels, and the influx of fresh, cooler water was too much for them to handle. That could be what pushed them over the edge.
By Thursday the remaining fish were feeding again. Unfortunately, most of them were smaller, 8 inches long or smaller. That goes along with what the biologist told me, the bigger, older fish were the ones that would die first.
If you have a pond and see the fish swimming near the surface during the day, they may be there because the oxygen level is low. About the only way to solve the problem is to put in an aerator. That is an expensive way to go, but it may be the only way to save the fish. I am checking on getting one for my pond now.
I really hated to lose all those big bream that I have had so much fun catching. But the biologist had some good news. The fish left will probably grow very fast now since there are fewer in the pond. Maybe I have something to look forward to!