Abstract:Robenidine hydrochloride(ROBH) is widely applied in treatment of diseases caused by sporozoan in freshwater aquaculture. In order to provide theoretical guidance for clinical rational administration in the breeding of crucian carp,pharmacokinetics of ROBH in Crucian Carp with body weight of(120 ±10) g was studied following oral administration of different doses (20 mg/kg, 30 mg/kg and 40 mg/kg) at water temperature of (25 ±1)℃. After administration, concentration-time cruves of ROBH in tested tissues of crucian carp exhibitied a "two-peak" pattern. The peak time, the maximum concentration and the area under the concentration-time curve of three doses in blood were as follows:20 mg/kg,Tmax=2.3 h,Cmax=0.55 μg/kg,AUC=9.35[(mg/L)·h];30 mg/kg,Tmax=2.1 h,Cmax=0.73 mg/kg,AUC=13.02[(mg/L)·h]; 40 mg/kg,Tmax=2.2 h,Cmax=1.17 mg/kg, AUC=13.98[(mg/L)·h]. Area under the concentration-time curve value from higher to lower in tested tissues were:kidney,liver,blood and muscle. The lowest rate of elimination was found in muscle, which was followed by blood. The fact that high ROBH concentration and long MRT were identified in kidney and liver suggested some kind of accumulative effect in both of these two tissues. According to the pharmacokinetics of ROBH in muscle, we suggest a withdrawal period of no less than 9 days in crucian carp. What's more, we suggest the withdrawal period can be adjusted properly because it might be influenced significantly by administration dose and temperature. This is the first pharmacokinetics report about ROBH in freshwater fish, which should be valuable in directing the application of ROBH for disease control.