Ulva fasciata and G. birdiae cultivated in outdoor tanks remove nutrient from seawater with a high efficiency and show satisfactory growth even in high thermal conditions, and can therefore act as a biofilter for the release of nutrients by fish. These species are suitable for RAS and IMTA to improve water quality and generate biomass. Methods to control the contamination of U. flexuosa cultures by microalgae must be investigated, since the feasibility of this species was previously reported