Residue and recoveries of clindamycin were investigated by reversed-phase high performance liquid chromatography (RP-HPLC) which was infected for the control of streptcoccal infection in Anguilla japonica and Paralichthys olivaceusis. Detection limit was 0.1 ppm. Recoveries of clindamycin in muscles of flounder and eel were 80.4 and 78.8%, respectively. The clindamycin in eel and flounder was detected up to 13 and 15 days after dosing, respectively.