This chapter examines Brazil’s marine fisheries, emphasizing the importance of marine biodiversity for seafood production productivity and sustainability. It highlights the complexities of marine fisheries, which are influenced by oceanographic and biological factors, leading to uncertainties in catch volume and timing. Despite contributing minimally to GDP, fisheries provide substantial employment and support millions indirectly. The chapter details the main landed categories, including sardines, croakers, and shrimp, discussing their production trends, management plans, and market importance. Brazil’s fisheries management has evolved since the 1960s, but weak enforcement and poor governance still pose challenges to guarantee a sustainable use of these natural resources. Effective management plans that consider the entire ecosystem are needed, and the creation of new Marine Protected Areas (MPAs) in 2018 is noted as a significant step. The chapter also covers seafood market dynamics, emphasizing the need for better market information, addressing mislabeling issues, and the role of supermarkets in securing sustainable seafood supply. The rise of aquaculture and imports as substitutes for wild-caught fish is noted, along with the importance of adding value through processing and reducing waste. It concludes by calling for better incentives, effective regulations, and informed consumer choices to develop sustainable fisheries and enhance marine biodiversity.