Floodplain water-bodies are major common-pool resources (CPRs) of Bangladesh and constitute more than fifty percent of inland open water bodies. Throughout the British colonial period, Pakistani rule and the first one and half decades of independent Bangladesh, a majority of inland water-bodies remained under direct government management, though the floodplains by getting heavily inundated during the monsoon turn into open access resource. In the mid-1980s co-management was introduced on a small scale with the help of NGOs as providers of management styles and credit to communities of fishers or villagers. NGOs also got involved in floodplain water-bodies and came up with different models of user-managed fishery bodies. This paper examines a specific management system of community-governed floodplain aquaculture (FPA) known as the Daudkandi model, developed by a local NGO in the Daudkandi sub-district of the Comilla district. Applying the design principles developed by Ostrom (1990) characterizing long surviving successful user-managed common-pool resource institutions, this paper explores the rules devised by partners in the management of a FPA under the Daudkandi model. Though the FPA management model is relatively new as it has been adopted in 1996, it has been found to follow the design principles in devising its management rules. However, because of its unique features in terms of seasonality, NGO-community partnership, exclusion of past users, and numerous replications, etc. the future of the model as a CPR governance system holds many challenges and deserves continuous research focus.