Small-scale fisheries and aquaculture have been recognized as important opportunities to enhance household food security in developing countries. While interventions aiming at promoting these activities reveal many positive effects, their direct and indirect impacts on nutritional status have not yet been fully documented. The objective of this paper is to identify more specifically the potential pathways that exist between fish-related livelihoods (small-scale fisheries, fish farming) and household nutritional security. The existing literature reveals scattered but increasing evidence of the contribution of fish to nutritional security through three distinct pathways. The first one is the direct nutritional contribution from fish consumption: because fish are rich in essential nutrients such as vitamin A, calcium, iron and zinc, households engaged in small-scale fisheries or aquaculture are, in theory, able to improve their own nutritional intakes by consuming some of the fish they capture or farm. The second relates to income: increased purchasing power through the sale of fish is recognized as critical for households to be able to access other foods and to improve their overall dietary intake. Finally, because the degree of control exercised by women over family income impacts directly on household food security and nutritional outcomes, enhancing the economic status of women through their involvement in aquaculture and/or fisheries-related activities (fish processing and trading) is also identified as another important pathway to improve household nutritional security. For these three pathways, however, evidence is often only anecdotal and therefore, the paper concludes by highlighting areas where further research and data are needed.