River encroachment in Barishal City has emerged as a critical environmental problem, drastically affecting aquatic biodiversity and the native ecosystem. The present study investigates the causes, consequences, and potential solutions to this issue. Barishal, with its extensive network of rivers like the Kirtankhola, Arial Khan, and Tetulia rivers, has traditionally relied on these rivers for transportation, farming, and trade. Despite this, augmented urbanization, industrialization, and unchecked building on riverbanks have led to the encroachment of the rivers. This, in turn, has caused habitat loss, reduced water quality, and disruption in the balance of ecology, severely threatening aquatic life. Added to this, the environmental consequence in the form of increased flood risk, modification of river flow regimes, and loss of important ecosystem services adds complexity to the issue. Preventing this crisis requires sustainable city planning, strict regulatory measures, and increased community awareness to promote the long-term conservation of Barishal's riverine ecosystem and aquatic biodiversity. Urgent recovery measures are necessary to prevent further degradation and ensure the sustainability of the region’s riverine ecosystem.