Vibriosis caused by Vibrio harveyi is still being a serious bacterial disease problem in the black tiger shrimp Penaeus monodon aquaculture. Due to this disease, the mortality of tiger shrimp post larvae can reach 100%. Attempt has been made for this bacterial disease prevention by using mangrove associates secondary metabolites. This study aims to determine potential of kopasanda (C. odorata L.) leaves as natural antibacterial against Vibrio harveyi. Potential study was carried out by determinination of the best solvent used to extract the bioactive secondary metabolites of kopasanda leaves, determination of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC). Toxicity study was also done by using soaking method to determine the save concentrations of C. odorata leaves on tiger shrimp post larvae. C. odorata leaves was extracted with methanol to extract all the active components, then, partitioned into n-hexane, ethyl acetate, methanol and aqueous extract. The highest antibacterial activity against V. harveyi was shown by methanol extract. The results suggest that C. odorata leaves have a potential to be developed as a raw material source for vibriosis prevention. It is due to its strong anti-vibrio activity showed by the low MIC and MBC of 0.625 and 1.250 mg/ml, respectively. Furthermore, the methanol extract did not show any toxicon tiger shrimp (P. monodon) post larvae up to 2.500 mg/ml.