Technical Abstract: Plasma distribution and elimination of florfenicol in channel catfish were investigated after a single dose (10mg/kg) of intravenous i.v.) or oral administration in freshwater at a mean water temperature of 25.4°C. Florfenicol concentrations in plasma were analyzed by means of liquid chromatography with MS/MS detection. After i.v. injection, the terminal half-life (t1/2), volume of distribution at steady state (Vss),and central volume of distribution (Vc) were 8.25 h, 0.9 and 0.381 L/kg, respectively. After oral administration of florfenicol, the terminal t1/2 , Cmax, Tmax and oral bioavailability (F) were 9.11 h, 7.6µg/mL 9.2 h, and 1.09, respectively. There was a lag absorption time of 1.67 h in oral dosing. Results from these studies support that 10mg florfenicol/kg body weight in channel catfish is an efficacious dose following oral administration.