Debates and decisions about food systems generally focus on agriculture and livestock. Yet, aquatic foods – fish, invertebrates, algae and aquatic plants captured or cultured in freshwater and marine ecosystems – play a central role in food and nutrition security for billions of people and are a cornerstone of the livelihoods, economies, and cultures of many communities. Despite their unique value and interconnections with terrestrial food systems, aquatic foods are often left out of food system analyses, discussions, decisions, and solutions. The 2021 Fuller Symposium explored the science behind the potential of aquatic foods to play a central role in ending malnutrition and in building healthy, nature-positive and resilient food systems.