In this work, essential oils of thyme (Origanum vulgaris), melissa (Melissa oleum), lavandula oil (Lavandulae romanae oleum), rosemary oil (Rosmarinus officinalis), ginger (Zingiber officinale) were screened for their chemical composition and in vitro antibacterial activity against Yersinia ruckeri, Aeromonas hydrophila, Vibrio anguillarum, Flavobacterium psychrophilum and Lactococcus garvieae. In this study, thyme (Origanum vulgaris), melissa (Melissa oleum) essential oils showed a stronger antimicrobial effect compared to other plant oils. The broadest spectrum of antibacterial activity was attained with oil of thyme (Origanum vulgaris).