In this FAO Fisheries Technical Paper, the present state of knowledge on the fish and fisheries of river systems is summmarized. It emphasizes the role of rivers as food producers; detailed analysis of the extensive literature on sport fishery management and practice is omitted. The first section deals with the physical and chemical environment and briefly summarizes aspects of primary and secondary productivity of rivers. The analysis of the biology and ecology of the fish concentrates on larger rivers; salmonid rivers are not examined in detail. Some models are presented as fishery scientists are increasingly called upon to make rapid proposals for management strategies or evaluations of possible impacts are of uses of the river and its basin other than fisheries. The last section examines the effects of the regulation and improvement of fisheries on the fish community; the social and economic implications of the various management approaches are not explored in detail. KEYWORDS: RURAL | Agricultural development | inland fishery | river basins | fishery resources | fishery management.