This chapter examines fish and seafood through a nutrition ecology framework (health, environment, society, economy), exploring global fish consumption and its importance in nutrition, food security, sustainability, and development.  It compares wild-caught fish with farmed (aquaculture), highlighting Atlantic salmon and shrimp, illustrating that overfishing and bycatch threaten ecosystems and biodiversity and have driven some species to near extinction.  While aquaculture meets eaters’ demands and provides livelihoods, sustainability practices vary, analogous to terrestrial agriculture (e.g., water pollution, antibiotics, sea lice, and animal suffering).  Seafood contamination from mercury and other persistent organic pollutants (POPs) and forever chemicals in the ocean can pose risks, but they are outweighed by health benefits, and omega-3s EPA and DHA are critical for pregnant women and children for optimal eye and brain development.  A dietary pattern including fish can be part of a heart-healthy diet, especially when replacing red meat; sustainable seafood guides inform environmentally sound, eco-conscious choices.