This research was conducted from Juni to October 2018, at Parasites and Fish Disease Laboratory, Faculty of Fisheries and Marine, University of Riau. The Purpose of this study was to determine the sensitivity of bay leaf (Syzygium polyantha) solution as antimicrobial to Aeromonas hydrophila, the range of Minimal Inhibitory Concentration (MIC) and the lethal dose (LD50) bay leaf (Syzygium polyan…