Blue food is too often left out of debates on food systems and food security. The physical inaccessibility of aquatic creatures, habitat and resources create their cultural invisibility - meaning their role in solutions goes unexplored, and key issues unaddressed. Learning from the Blue Humanities, IIED Researcher Giulia Nicolini calls on us to think blue food back into food systems - and so into their transformation. This essay draws on IIED’s ‘What about seafood?’ paper and work on aquatic foods. Giulia Nicolini is a researcher at the International Institute for Environment & Development (IIED). She works at the intersection of food and environmental issues, including blue foods and their role in the future of the UK food system. Giulia is also a PhD student in Anthropology at the University of Exeter, based in the Centre for Rural Policy Research. Her doctoral research explores how taste and demand for seaweed as a food are changing in the UK.