Finding ways to feed a future population of 10 billion people a healthy diet within planetary boundaries has become an urgent global priority. Doing so will require radical transformation of food systems. The Food Systems Summit, to be convened by the United Nations in November 2021, will launch global dialogues and actions that aim to transform the way the world produces and consumes food, in ways that contribute to the Sustainable Development Goals, including SGD14 – Life Below Water. This article outlines the characteristics of capture fisheries and aquaculture and the contributions that aquatic foods make to food and nutrition security, and livelihoods in the Global South, and makes the case for the importance of viewing both through a food systems lens.