RESIDUES OF OXYTETRACYCLINE IN WILD FISH AND SEDIMENTS FROM FISH FARMS

The residues and persistence of oxytetracycline were studied in wild fish and sediments on two fish farms after chemotherapy of the farmed fish. In wild fish, residues of oxytetracycline were detected up to 13 days after the medication. The half-life of oxytetracycline in fish farm sediments was 9 days and 419 days on the two farms, respectively. The results indicate that oxytetracycline may, under stagnant anoxic conditions, be very persistent in fish farm sediments. It is suggested that leakage from sediments, not decomposition, may be the main factor reducing the oxytetracycline levels in sediments. Bacteria, resistant to oxytetracycline, were isolated from the intestines of wild fish. © 1990.