This study investigates the bacteriological quality and histamine levels in tuna fish, highlighting significant health risks associated with bacterial contamination throughout the fish's lifecycle. Bacteriological analysis of three tuna samples revealed the presence of pathogenic bacteria, including Escherichia coli (2/3), Salmonella (1/3), Staphylococcus aureus (2/3), and Proteus species (1/3). Histamine levels were assessed using ELISA, with concentrations recorded as 18.05 mg/100g, 27.4 mg/100g, and 20.1 mg/100g, indicating that one sample exceeded the permissible limit of 20 mg/100g as per EOS guidelines. The study further explored the efficacy of essential oils, specifically thyme and blackberry oils, in reducing histamine levels in contaminated fish. Results demonstrated that thyme oil at 1% concentration significantly reduced histamine levels by 58.6% over nine days, while blackberry oil at 1% achieved a reduction of 46.1%. These findings suggest that essential oils can effectively mitigate histamine accumulation and microbial growth in tuna fish, presenting a promising approach to enhance food safety and extend shelf life. The study underscores the importance of monitoring bacterial contamination and histamine levels in tuna to ensure consumer safety and improve product quality through natural preservation methods.