This 2021 annual report describes the key achievements of the CGIAR Research Program (CRP) on Fish Agri-Food Systems (FISH). During 2021, FISH focused on several key areas to achieve a successful and impactful closure of the program: (i) completing key lines of research, (ii) accelerating the transition from discovery to enable the uptake of research and policy advances, (iii) assessing impacts and analyzing projected benefits, and (iv) managing the multiple challenges of the COVID-19 pandemic across the FISH portfolio.