Antibiotic residuals in some farmed rainbow trout (Oncorhynchus mykiss) of market size in Iran

To assess the hygienic conditions of market rainbow trout (Oncorhynchus mykiss), the residuals of three antibiotics consisting of oxytetracycline (OTC), enrofloxacin (EN) and erythromycin (ET) were measured in the muscles of freshly caught fish obtained from 17 trout farming in Charmahal-va-Bakhteyari (CVB) province using high performance liquid chromatography. Totally 266 fish samples were randomly obtained and 798 muscle samples were used for detection of the above antibiotics. The obtained results showed that OTC was detected in one fish farm (5.8%) having a residual of 0.75 to 7.13 ?g g-1. EN was detected in 6 fish farms (35%) with a residual of 0.5- 0.73 ?g g-1. Also, the lowest and highest residuals of ET were 23.38 and 181.38 ?g g-1, respectively in 5 fish farms (29.4%). The obtained results showed that the residual of these antibiotics in trout muscles of some fish farms were higher than the acceptable levels and therefore, requires a serious attention of both the environment and the consumer health care. Also, the detection limit of 0.05 ?g g-1 used for these antibiotics shows that application of high performance liquid chromatography method used here in this study is a useful tool for a routine screening of these antibiotics in trout farming.