In this study, we prepared silver nanoparticles immobilized onto silica sand beads as an antibacterial material against pathogenic luminous Vibrio sp. Persian1. Silica beads were modified with 3-aminopropyltriethoxysilane (APTES), cyanuric chlorid and tetraethylene pentamine, and silver nanoparticles were generated in various concentrations (0.5, 1, and 2 mM g−1 of silica beads) of AgNO3 on the surface using chemical reduction. Ag/TEPA-Den-SiO2 samples were characterized by TEM, FE-SEM/EDS, FT-IR and ICP OES and their antibacterial activity assayed by zone of inhibition and test tube tests against pathogenic Vibrio sp. The results of the zone inhibitory test revealed that all the Ag/TEPA-Den-SiO2 samples had an antibacterial effect against luminous Vibrio sp. Persian1. In addition, the tube test results showed 100% killing of bacteria in 2 h contact period. Ag/TEPA-Den-SiO2 samples maintained their antibacterial activity after 14-day immersion in seawater by slow release of silver ions. These results suggest that Ag/TEPA-Den-SiO2 substrates could be effective antibacterial materials for disinfection of seawater used to culture Penaeid shrimp larvae.