In this article, the author wants to reveal the complex ecology of the upper Mekong in Cambodia as a case study, especially in Stung Treng province where it is considered as the conservation zone in term of fish and biodiversity resource management. That is, the paper aims to investigate the following objectives: (1) to examine the local fishermen’s livelihood strategies and their cultural practices and how they adapt themselves to the changing property regimes in the province, (2) to contextualize the policy and fisheries management by the state and to show how such a policy gives right to the changing property relations, (3) to revea ldifferent strategies developed by different actors (including NGOs program related to fishery managementin the province) in gaining access to fisheries management.