Winter Fish Kill Prevention

winter fish kill prevention with aerationAs a pond or lake freezes, a winter fish kill can happen as diffusion of oxygen from the air above is cut off. If snow builds up on the ice, or the ice becomes hazy, light can’t penetrate the ice. This cuts off the production of oxygen by plants as well. Bacteria consume oxygen as they break down dying plants. Then fish consume more oxygen and the lake or pond is in trouble causing more fish to die.

Aeration Prevents Winter Fish Kills

In winter months, non-aerated ponds exhibit a type of reverse-stratification in their water column. The water is warmer, and slightly denser at the bottom. A Vertex winter pond aeration system brings warmer water to the surface to melt a hole in the ice. Open areas of water increase oxygen levels to prevent a winter fish kill. The hole size depends on several factors including, but not limited to, air temperature, depth and number of diffusers, and amount of airflow.

Where do I install the AirStations?

In the winter water is warmer closer to the bottom, this is where the fish will generally seek refuge from the extreme cold. It is important to locate the diffusers in an area where water depth is not at its deepest (~4′) to prevent rapid “super-cooling”. Super cooled water leads to fish kills. Place your diffusers in shallower water to preserve this deeper, warmer, safe haven for your fish while still opening a hole for gas exchange.

Prevent Winter Fish Kills


Vertex Aquatic Solutions, founded in 1977, is the professionals’ choice for research based scientific consulting services, aeration systems, floating fountains, bubble curtains and biological products to enhance water quality in lakes, ponds, canals, marinas and reservoirs. As respected leaders in the lake management industry the Vertex team of aquatic biologists, limnologists, fisheries scientists and engineers work together to deliver science-based, environmentally sound solutions to complex waterbody issues. Our products and services are delivered through an international network of qualified, experienced waterbody professionals who provide local support, service and pond management expertise to customers.

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