The use of plants with therapeutic components has been widely recorded throughout history. Examples of the above are plants such as thyme, lemongrass, and oregano, whose antibacterial and antifungal properties have been reported in traditional medicine. The increasing incidence of antimicrobial-resistant microorganisms and the strict drug regulations in the aquaculture industry have prompted research into the bacterial inhibitory capacity of plant-derivates. In the present study, the effect of three phytocompounds (thymol, citral, and carvacrol) were tested against Edwardsiella ictaluri (S97-773), E. piscicida (S11-285), Aeromonas hydrophila (ML09-119 and S14-452), Streptococcus agalactiae (RUSVM-CV), S. iniae (LSU 01-105, LSU 10-070, LSU 94-034, LSU 96-525, LSU 94-0.36), S. ictaluri (CNA2848) and S. dysgalactiae subsp. equisimilis (STC3). The inhibitory effects of these biomolecules were evaluated using the disk diffusion test [50 mg/ml] and broth microdilution tests [1.56 mg/ml]. After this, the inhibition of bacterial biofilms was determined using gentian violet; the inhibition of hemolytic activity was determined using blood agar (brain heart infusion) and they were quantified using the liquid hemolysis assay. All phytocompounds inhibited bacterial growth in the disk diffusion tests (p<0.01), with citral presenting the smallest inhibition zones. These results were corroborated by determining the minimum inhibitory concentrations (MIC) and minimum bactericidal concentrations (MBC), where citral required higher concentrations compared to carvacrol and thymol. In the biofilm inhibition test, fractions of the observed MICs significantly reduced the adhesion of pathogenic bacteria to the microplates. A significant reduction of hemolysis by relevant bacterial species was observed upon exposure to the phytocomponents. Scanning electron microscopy and quantitative PCR assays focused on biofilm formation and virulent genes are pending. These preliminary data show promising results, where supplementation of these plant products in culture media, even at concentrations lower than the observed MIC, can significantly impact the survival and virulence of an array of fish bacterial pathogens. These findings will serve as a basis for future research investigating their dietary potential as antibiotic alternatives to manage bacterial infections for cultured fish. Such alternatives may assist in mitigating selective pressures that contribute to antibiotic resistance in aquaculture.