Edwardsiella piscicida is a common marine pathogen infecting diverse fish species, causing hemorrhagic septicemia and substantial economic losses to the global aquaculture industry. The hemolysin proteins (EthA) and type III and VI secretion systems (T3SS/T6SS), controlled by the EsrA‐EsrB two‐component system (TCS), are essential for bacterial colonisation and host invasion. This study demonstrates that the UvrY‐BarA TCS nega...