The aim of the study was to assess some chemical parameters in water from Tundzha River used for common carp (Cyprinus carpio L.) farming. Water samples were taken according to protocol in September 2014 from the fish farm located near the town Nikolaevo. Results showed compliance with regulations for most of the studied parameters. A slight increase of ammonia (NH3) was found in the control sample. In both locations elevation of nitrates (NO3) and phosphates (PO4) was registered, suggesting contamination of the water from agricultural use of organophosphate insecticides and nitrogen fertilizers. In conclusion, effective measures should be taken to protect water resources in Tundzha River used in fish farming from agricultural pollution
