This paper examines recent conflicts over freshwater fisheries in Cambodia using the notion of accumulation through dispossession as a conceptual starting point. Despite a recent material turn, theoretical literature on the political economy of the environment has only partially incorporated an ecologically nuanced view of nature into analyses of its transformation under processes of capital accumulation. The biophysical characteristics of riverine fisheries are predicated on the ecohydrologic dynamics of water flows, and these characteristics dictate strategies of appropriation for both subsistence and commercial use. The complexity of these material characteristics is compounded in the case of Cambodian fisheries, where an array of state- and market-driven processes promote the dispossession of resources and constrain the livelihood opportunities of rural communities dependent on fishing. Theories of capital accumulation and how accumulation induces socioecological conflicts can be very useful, firstly, for explaining the origins of environmental conflicts and, secondly, for grounding the analysis of such conflicts in the politics of accumulation as mediated by state actors. Conversely, theoretical framings of primitive accumulation must examine the “things” being accumulated (eg riverine fisheries) in far more biophysically specific ways, and must recognize the circuitous pathways, particularly in cases involving developmental states, that strategies of accumulation follow.