Winter Kill in Channel Catfish Winter Kill in Channel Catfish Disease Symptoms Winter Kill Syndrome is a serious disease affecting farm-raised channel catfish during colder months. Clinical signs of the disease are easily recognized and are exhibited as dry skin, sunken eyes, and skin lesions that appear as white to yellow cottony patches. Internally, the intestinal tract is empty, and a clear, watery fluid is present in the gut. Although all sizes of fish can be affected, the disease occurs most frequently among fish of harvestable size. Empty stomach and intestine with watery fluid Diffuse skin hemorrhage White to yellow cottony patches on skin Causes of Disease Previous exposure to significant stress during the summer or fall, physical injury, preexisting illness, and inadequate nutrition appear to predispose fish to disease in the winter.
Fungi are everywhere in natural waters and commonly grow on dead organic material.
However, several species can act as primary disease producers for catfish. Evidence from diagnostic records and from laboratory and field studies involving commercial catfish ponds indicates that the occurrence of Winter Kill appears to depend on two major factors. Seasonal Influence on Pond Temperature Because the high water temperature observed during the summer appears to optimize catfish defenses, development of the disease rarely occurs in summer. Generally, mortality remains low until pond temperatures begin to increase and stabilize in late winter and early spring. The mortality observed during the winter is the result of environmental and biological interactions that took place several months earlier.