Abstract: Seaweed-associated marine bacteria were recognized as a potential source of antimicrobial compounds. In the present study, a total of 27 epiphytic bacteria were isolated from four species of seaweeds collected from the Kollam coast (Indian Ocean) were investigated for antagonistic activity by cross streak method. Of the 27 bacterial isolates, 4 strains inhibited the growth of at least one shrimp vibrio pathogen tested. The active strains were further subjected to agar well diffusion assay. The result indicates that among the four seaweed isolates, SWI-24 strain exhibited highest spectrum of activity against all the tested shrimp pathogens. The molecular characterization based on partial 16S rRNA sequence revealed that the active isolate SWI-24 was Pseudoalteromonas sp. The efficient antagonistic potential exhibited by the SWI-24 against pathogenic shrimp bacteria may further reflect the potential use of seaweed-associated bacteria in managing the shrimp/fish disease.