Occurrence of antibiotics in water from 13 fish hatcheries, 2001-2003

A 2- year study of extensive and intensive fish hatcheries was conducted to assess the general temporal occurrence of antibiotics in aquaculture. Antibiotics were detected in 15% of the water samples collected during the 2001 - 2002 collection period and in 31% of the samples during the 2003 collection period. Antibiotics were detected more frequently in samples from the intensive hatcheries ( 17 and 39%) than in samples from the extensive hatcheries ( 14 and 4%) during the 2001 - 2002 and 2003 collection periods, respectively. The maximum ormetoprim, oxytetracycline, and sulphadimethoxine concentrations were higher in samples from the intensive hatcheries ( 12, 10, and 36 mu g/L-1), respectively, than in samples from the extensive hatcheries (< 0.05, 0.31, and 1.2 mu gL(-1)), respectively. Sulphadimethoxine persisted for a longer period of time ( up to 48 days) than ormetoprim ( up to 28 days) and oxytetracycline ( less than 20 days).