The scale and speed of human activities and technological developments have substantially increased since the 1950s resulting in reshaping of the biosphere and moving humanity into a new geological epoch — the ”Anthropocene”. This is characterized by changes in several Earth system processes and structures on which human life depends. The global food system is a major driver of changes in the biosphere – for example greenhouse gas emission and other environmental changes including global biodiversity loss. Blue foods (aquatic foods) have slowly made their way into international high-level sustainability discussions and increasingly now form part of nutritious, climate smart and low environmental impact food narratives. Today farmed and captured aquatic animals and plants play a central role in food and nutrition security for billions of people, and constitute cornerstones for many livelihoods, economies, and cultures. The blue food portfolio is highly diverse and also supported by a wide range of ecosystems, cultural practices and production modalities. This diversity poses both potential for supporting food system resilience in uncertain times, and challenges for making simple guidance on sustainable development of food production. The anticipated continuous growth of aquaculture trigger questions related to “what, how and why”. Many blue foods are rich in bioavailable micronutrients and can be produced in ways that are more environmentally sustainable than some terrestrial animal-source foods. However, blue foods are diverse and planning for future expansion through i.e. aquaculture involves identification of properties for different species and systems, as well as identification of development priorities and acknowledging trade-offs and context specificity out from a broader Sustainable Development Goal framework. Environmental stressors may narrow the window for blue food production and climate change is a main driver affecting the function and productivity of aquatic and supportive terrestrial ecosystems.