This study explored the use of brines from tuna canneries as a nutrients source for the culture of a marine protist isolated from coastal waters of Bizkaia (Basque Country, Spain). The process yielded 5.5 g/L of biomass with 8 % of nitrogen (2.8 g/L protein) in 168 h. Although under control conditions the biomass achieved was 45 % higher, brine provided amino acids, vitamins and phosphate allowing the simplification of the culture medium to glucose, trace metals, water and brine. This reduced the cost of the medium by 90 % saving 40 % of water in the process. These results provided a revalorisation strategy for an industrial wastewater difficult to manage coupled to obtaining a protein-rich biomass.