Aquaculture Europe 2025 September 22 - 25, 2025 Valencia, Spain E. Troianou1*, E. Abatzidou1 and I. Tzovenis1,21Kefalonia Fisheries SA, Samoli Livadi, Lixouri 28200, Greece2Microphykos, Halandri, Athens 15238, GreeceE-mail: e.troianou@kefish.grIntroductionEffluent from marine hatcheries, such as those rearing Mediterranean seabass (Dicentrarchus labrax), still after treatment. contains considerable levels of inorganic nutrients which could contribute to coastal eutrophication. Integrated multitrophic aquaculture (IMTA) offers a sustainable solution by incorporating extractive species to recover nutrients. The green macroalga Ulva spp., with its high nutrient uptake efficiency and rapid growth under variable Mediterranean conditions, is an ideal candidate for such systems (Shpigel et al, 1993).This work evaluates the cultivation of Ulva using seabass hatchery effluent to remove inorganic nutrients while producing biomass for biomaterial applications. We quantify nutrient removal performance, assess biomass yields, and discuss the potential of integrating Ulva production into IMTA frameworks to enhance environmental sustainability and circular bioeconomy outcomes in Mediterranean aquaculture.