Book excerpt: This publication reviews the potential for fisheries production from irrigation canals. It deals with the subject under the following major headings: engineering aspects of irrigation systems; factors limiting fish production in canals; weed growth and associated problems in irrigation canals. Cage culture in irrigation canals is presented in case studies for Indonesia, Egypt and Thailand, and pen culture in China. Both cage and pen culture are considered to be the most suitable forms of aquaculture in irrigation canals. Fish can be profitably and successfully reared in irrigation canals to control unwanted aquatic weed growth, and there is some potential for the use of fish to control vectors and hosts of waterborne diseases. Amongst the constraints, levels of pesticides in fish tissues cultured in irrigation systems could be a problem in the development of foodfish production in irrigation canals. The major constraint to aquaculture development in such systems is that a continuous, preferably constant, flow of water is required throughout the culture period and this is not available in many irrigation systems.