Capture fisheries are constituted through historically specific environmental conditions and social and economic relations of production. Fisheries, whether saltwater or freshwater, are an important source of animal protein, livelihoods and exchange value in international trade, and are presently undergoing rapid socio-ecological change. To explore the political economy and ecology of capture fisheries around the world, this paper synthesizes the insights of 11 empirical studies and places fisheries in the broader context of the capitalist relations of production through which they operate. The competitive market dynamics of fisheries production and consumption are examined, as well as the forms of social-property relations, social differentiation, labour exploitation and resistance that occur within them. This paper highlights some of the ways in which the unique combination of characteristics associated with fish and fisheries complement and complicate familiar questions in agrarian political economy. It concludes by identifying future research directions.