The primary cause of loss of biodiversity in aquatic systems is habitat degradation, primarily due to factors such as pollution, overfishing, and climate change. Water quality degradation from agricultural runoff, industrial discharges, and urban development significantly reduces the survival of aquatic species. Overfishing depletes fish populations, disrupting ecological balance and food webs. Moreover, climate change introduces stressors like rising temperatures and altered water salinity, further threatening species. Addressing these issues through sustainable management practices is vital for conserving aquatic biodiversity and maintaining healthy ecosystems.