Bangladesh, a leader in global fish production, faces significant post-harvest losses that adversely affect farmers and traders in the haor region. This study evaluates post-harvest losses among fish farmers and investigates the underlying factors contributing to these losses through a survey of 450 fish farmers and 150 traders. Descriptive analyses reveal notable disparities, with Netrokona district experiencing 34 % physical losses, while Kishoreganj and Sunamgang districts contend with market force losses of 50 % and 40 %, respectively. Insights from Bepari (small-scale traders), Paikar (rural and urban retailers), and general retailers highlight distinct concerns, including a reported 41 % market loss among Bepari, 38 % quality loss emphasized by Paikar, and 40 % market and 30 % quality losses faced by retailers. Farmers attribute these losses to factors such as elevated temperatures and destructive fishing practices, while market participants identify challenges like inadequate storage and transportation delays. A multiple regression analysis reveals critical influencing factors, indicating that age, education, training, and improved transportation positively affect post-harvest outcomes, while selling in secondary and tertiary markets also enhances results. Interestingly, greater labor availability correlates with increased post-harvest losses, potentially due to handling inefficiencies or lack of coordination among workers. This study underscores the necessity for policymakers to devise targeted strategies that address the unique challenges of the haor region, thereby reinforcing Bangladesh's position in global fish production and ensuring the economic sustainability of its farmers and traders.