This research was conducted in October-December 2023 at the Marine Microbiology Laboratory, Faculty of Fisheries and Marine Sciences, University of Riau. The purpose of this study was to analyze the effect of adding guava leaves (P. guajava) on the hematology and survival rate of carp (C. carpio) kept in brackish water and to determine the effect on the hematology of carp (C. carpio) infected w…