Two individuals of mud crab Rhithropanopeus harrisi (Gould, 1841) caught in March 2016 and September 2017 in the Kuchurgan cooling pond of the Moldovan Power Plant are the first finds of this alien species in water bodies of Moldova and Transdniestria, which naturalized in the brackish waters of estuaries of Europe and the Black Sea. A likely explanation for the emergence of these individuals in the Kuchurgan Reservoir appears to be an accidental introduction at a larval stage during stocking of mullet from the Khadzhibei estuary. The thermal regime and mineralization of the Kuchurgan Reservoir will possibly promote an inclusion of the mud crab in the structure of the reservoir aquatic biocenosis.