The pharmacokinetics of marbocyl were studied following intravenous and intramuscular (single and repeated) administrations. Following a single intravenous injection of 10 mg/kg body weight of marbocyl in normal catfish (Clarias Lazera), serum concentration-time curve was best described by two compartments open model with elimination halflife (t0. 5β), volume of distribution (Vdss) and total body clearance