In this study, certain water quality parameters (water temperature, dissolved oxygen (DO), pH, total inorganic nitrogen (TIN), phosphate (PO4), nitrite (NO2), nitrate (NO3), ammonium (NH4), and (BOD5) in the effluents and the efficiency of the treatment systems for eliminating wastes at a commercial trout farm with a capacity of 10 tons/year in Izmir (Kemalpasa) were examined. The DO, temperature, pH, TIN, PO4, NO2, NO3, and BOD5 measured, were different in the outlet waters when compared with the inlet waters (p<0.05). The settling basin did not reduce the TIN and PO4, on the contrary, it caused an increase in the nitrogen (N) up to 19.9% and phosphorus (P) up to 20.30%, while the wetlands reduced the N, P, and BOD5 up to 53.2%, 58.2%, and 36.5%, respectively (p<0.05). According to the chemical and biological methods, the averages of the TIN and P loads for one tone of cultured trout without treatment were estimated to be were 80 kg and 7 kg, respectively. The annual TIN load of this trout farm was estimated to be 21.3 kg while the TP load was 2.9 kg for one tone of cultured trout when the treatment efficiency was taken into account. The microbiological analyses conducted with the effluent waters showed that the rate of aerobic mesophilic bacteria was found to be high in the summer but low in the winter. It was also detected that the coliform group bacteria were present in the environment in the summer while their occurence was with-in standards in the winter.