Fish is an important food for human consumption. Because of its high nutritional value, it can treat diseases caused by malnutrition, and it is especially suitable for children, pregnant women and breastfeeding mothers. More than one billion people around the world get their animal protein requirements from fish, which also contains minerals like phosphorous, iodine, calcium, magnesium and sulfur. In addition, there are a number of important fat-soluble vitamins in fish oil, including vitamins A and D. Fish oils are high in unsaturated fatty acids, especially omega-3, which helps reduce cholesterol. Yet despite being highly nutritious, fish is difficult to process and spoils easily. This is why proper processing methods are so important, as they help preserve fish, prolong its shelf life and produce new products that consumers prefer. Fish processing also engages more women and youths in aquaculture activities, which improves their income. This manual was prepared through the Advancing Climate Smart Aquaculture Technologies (ACliSAT) project, funded by the International Fund for Agricultural Development. WorldFish is implementing the project in partnership with the Central Laboratory for Aquaculture Research in Egypt, Bahir Dar University in Ethiopia and the Ministry of Marine Resources in Eritrea.