The liquid chromatography-mass spectrometry (LC-MS/MS) for sulfamonomethoxine (SMM), sulfadimethoxine (SDM) and sulfamethazine (SMT) has been established in this study. The detection limit for SMM, SDM and SMT was 4.17, 2.60 and 2.69 ppb, respectively. The linearity range (0-30ppb) for SMM, SDM and SMT was >0.99. The sufonamides in fish tissues were determinated from 1-32 days after withdrawing the medicated-feed treatment. The sulfonamides could not be found in all the fish tissue samples in the 32 days.