Aquaculture productivity is limited by the introduction and spread of infectious fish diseases, which compromise fish farming livelihoods and food and nutrition security in Asia and Africa. Epidemiological tools provide valuable data to understand risk factors for fish disease outbreaks and losses, contributing to improved policies and management measures. Using rapid diagnostic tools for early detection of fish pathogens can help hatchery and nursery operators as well as farmers take timely action to reduce the spread of disease. Data pipelines emerging from epidemiological and diagnostic tools provide a foundation for new solutions and practical management actions to control fish diseases. Implementing better management practices at the farm level will significantly reduce disease-related losses. This requires a major change in integrating and disseminating practical disease control measures in aquaculture extension and vocational training programs.