Histamine poisoning is a common seafood-borne illness worldwide, and Morganella morganii subsp. morganii is one of the most probable histamine producers. Bacteriophages are bacterial viruses that kill the host cell after infection. In this study, we evaluated the effect of M. morganii phage FSP1 treatment on histamine accumulation by M. morganii in raw tuna meat. M. morganii was inoculated to tuna meat and incubated at 4, 12 and 20°C to evaluate the inhibitory effects of FSP1 on the growth and histamine accumulation of M. morganii. Viable M. morganii counts were decreased significantly in response to FSP1 treatment under all conditions. Furthermore, histamine concentrations in phage-treated samples were significantly lower than those of control samples. FSP1-resistant M. morganii did not develop after FSP1 treatment. These results suggest that phage treatment might be an effective tool to reduce the risks of histamine poisoning by M. morganii in fisheries products.