Fertilization of farm ponds also increases the risks of

Fertilization of farm ponds also increases the risks of “summerkiir or “winterkill” of sport fish. During extended periods of calm, cloudy weather or snow-covered ice, decomposing weeds may consume all of the available dissolved oxygen, causing fish to suffocate.

Because sport fish are the most sensitive to lowered oxygen levels, they will be affected before undesirable species such as carp. Dense weedbeds that restrict water movement and reduce aeration result in warmer water and further reduce oxygen supplies in the pond waters.

Fish stressed by these conditions are most susceptible to disease and parasite infections.

Probably the biggest single myth about fish ponds is that small fish are the result of “unproductive” pond waters. Fisheries managers know that the sizes of fish in a pond are determined by the ratio of predatory fish to prey fish - what is called “balance.”

Good growth of sport fish depends on the presence of large predators which reduce the abundance of small fish, leaving more food for the survivors.

Without predators, fertilization will produce only more small fish competing with one another for food, preventing them from ever growing to a desirable size for fishing and eating.

To make matters worse, the weedbeds produced by fertilization provide refiige for small fish so that fish like largemouth bass cannot prey effectively. Thus, neither the small prey fish nor large predatory fish will grow well in weedy ponds.

In the past, popular articles on fish pond fertilization have tended to oversimplify the proper procedures, overlook the unnecessary costs involved, misrepresent the results to be expected and neglect to discuss the problems created by over-fertilization. In reality, a successful fertilization program is likely to be much more complicated than pond owners imagine.