Environmental load of wels (Silurus glanis) fed by feeds of different protein levels

The most dangerous effect of the environment on traditional and intensive fish farming is thereleased nutriment loaded effluent water. Intensity is increased and the nutriment intake by artificialfeeds cannot be utilized all by fish. Parts of these remain in the system in particulate or dissolved formand begin to accumulate, may cause insufficient water quality. During our experiment we examined theenvironmental effects of three different feeds of different protein levels. The declared crude proteincontents of feeds were 33%, 40% and 49%. At the beginning of our research, catfish were fed by feedsof 1% of bodyweight. We measured the inorganic dissolved nitrogen forms of water before addingnourishment and after in the 6th, 12th, 24th, 36th, 48th, 60th and 72nd hours. Before sampling wechecked the main physical and chemical parameters of water which are essential to analysis. With regardto the results, the concentrations of ammonium nitrogen were permanently increased in control and alsoin the other treatments during the 72h examined period.