In IMTA-RAS, macroalgae (e.g. Ulva spp) act as a biofilter by reducing the inorganic components (N, P and CO2) issued from the metabolic activity of fish. Moreover, macroalgae can contribute to the microbial balance of the systems and disease prevention. The webinar will present research focused microbial management strategies in IMTA-RAS, based on Ulva-epiphytic bacteria such as those from the Phaeobacter genus that produce tropodithietic acid (TDA) with antagonistic activity against pathogens. The research approach involves from field sampling to aquaria experiments and metagenomic and metabolomic techniques.