Age features of pathogenesis of saprolegniosis in brook trout (Salvelinus fontinalis Mitchill, 1814)

Abstract

The data about the disease of saprolegnia of caviar and juveniles of brook trout are present. Saprolegniosis develops not only on the dead, but also on living eggs and free embryos lying next to each other. After separation of the live from dead eggs and clean them from fungus, embryos in them developed with disorders, died and then resolved. With the development the juveniles infects with saprolegnia rarely. The fungus develops on the fins, tail stalk and near the fins of fish. Yearlings are more resistant to adverse environmental factors, but at higher planting densities they are injured. These conditions are favorable for the rapid development of saprolegnia (about 1,5 days). During this period, there is a lifetime necrosis of tissues, destruction of fin blades and operculum. These individuals located in the corners of the aquarium and practically did not eat. The negative impact of the fungus on the superficial somatic musculature was found. On the histological sections of the muscles made directly under the lesion of the fungus skin, the destruction of muscle fibers and the accumulation of a large quantity of histiocytes in the endomysium are noticeable. There is need for further studies of saprolegnia and finding effective methods to eliminate it in different species of fish.