Fish kill is a widespread problem for many pond owners, but it’s not just from the winter freeze. Fish kill can also occur in the hot summer months; and with summer approaching we want you to know how it can be prevented.

Many pond owners have experienced winter fish kill, and the cause is well known. In the winter ice and snow cover the pond which blocks sunlight from penetrating into the water, limiting photosynthesis. When this happens, there is a lack of oxygen that is being produced; water is cold, oxygen is low, fish are in a stressful state and many can die. For winter we have the ideal solution. Natures Pond Conditioner Fall/Winter Blend cleans ponds of runoff and debris, and decomposes organic matter before the freeze up. Paired with bottom up aeration which oxygenates the pond, the risk of winter fish kill can be dramatically reduced.

The Koenders windmill was a great purchase, - I am a snow bird now and last winter when I went away in December, the pond was frozen, it was a very cold winter, thick ice, and when I came back 3 of my neighbours had major fish kills, one of them lost all of his fish. I am so glad I got one of your aeration windmills, I didn’t lose a single fish!! – C. Barber, Oxford, NY.

So, if lack of sunlight is the culprit in the winter, why does fish kill happen in the summer when sunlight is abundant? One cause of summer fish kill could be a result of the treatments you use. Herbicides and algicides are common practice for some pond owners, but are far from the best solution. They are designed to kill off unwanted aquatic plants and algae to clean the pond. But killing the plants with chemicals actually ads fuel to the fire of your pond problems. When the aquatic vegetation dies it sinks to the bottom of the pond, adding a layer or organic matter and sludge that must be consumed by the natural bacteria in the pond. Bacteria are living organisms that require oxygen, so when it is working hard to consume the organic matter its also consuming lots of oxygen from the pond. All the aquatic vegetation has been killed, and there is nothing to produce oxygen in the pond. The now oxygen depleted pond can easily cause a fish kill.

Another cause of fish kill in the summer could be due to stratified pond water. In the summer the top layers of a pond are warm and the bottom of the pond is cold, this is called stratification. The cold water at the bottom has less oxygen than the top layer, and fish spend most of their time in the top layers. If a summer storm hits the pond; wind and rain can stir up the pond, de-stratifying the water. When the two layers are mixed, the oxygen levels are lowered dramatically. Where oxygen was before, it is no longer there and a fish kill can ensue.

So what can pond owners do to prevent fish kill in the summer? First, they must understand the problem, whether its caused by herbicides and algicides, or stratification, a lack of oxygen in the pond is the main cause of summer fish kill. The best solution to an oxygen depleted pond is bottom up aeration. Bottom up aeration restores pond oxygen levels, by infusing oxygen into the bottom of the pond. The bottom up motion that aeration creates can also prevent stratification of the pond temperature and limit algae growth. Instead of tackling unwanted aquatic vegetation with herbicides and algicides, manually remove plants and weeds with a Cutter n’ Rake. This way, organic matter will not be added to the bottom of the pond. Natures Pond Conditioner Spring/Summer Blend can also be used to clean and clear the water without causing harm.

I constructed my pond in the late 1980’s with my father, and made it about 1/3 of an acre in size. We wanted it for fishing, recreation and swimming, so have stocked it over the years with a variety of different fish such as blue gill, crappie and catfish. We noticed that we would lose some of our fish each year during the hot months of July and August. IN 2006 we finally decided it was time to address that problem and we installed a Koenders Windmill Aeration System - and we haven’t experienced any more fish kills since installing! -Rob McClure, Carrollton, OH.

Summer is almost here and it is the best time to implement a care program to prevent problems like fish kill before its too late. Nature’s Pond Care 3-step program is proven to reduce the risk of fish kill and keep ponds clean and clear all year round. 

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