The purpose of this project is to establish the pharmacokinetic model of macrolide antibiotics in pretreated cobia. We will also set up the experimental animal model, sample collection, extraction and analysis techniques in live cobia. According to the analytic results, we will establish the pharmacokinetic model to evaluate the macrolides residues in the tissues in cobia. The final results will provide the reference to the government for defining the standard macrolides withdrawal period in the guideline.