Freshwater Fish Biodiversity: Conservation Challenges, Emerging Threats, and Sustainable Management Approaches

Freshwater ecosystems occupy less than 1% of the Earth’s surface yet support nearly half of all fish species and provide essential ecosystem services that sustain biodiversity, food security, and human livelihoods. Freshwater fishes play vital ecological roles in nutrient cycling, food-web regulation, and maintaining ecosystem stability while contributing significantly to fisheries, aquaculture, recreation, and local economies. However, freshwater fish diversity is declining at an unprecedented rate due to habitat degradation, river fragmentation, pollution, climate change, overexploitation, invasive alien species, and altered hydrological regimes. These pressures have resulted in population declines, local extinctions, and reduced ecosystem resilience across many river basins worldwide. Recent advances in molecular biology, environmental DNA (eDNA), remote sensing, Geographic Information Systems (GIS), artificial intelligence, and conservation genomics have significantly enhanced freshwater biodiversity assessment and monitoring. This review summarizes the ecological importance of freshwater fish biodiversity, examines major threats to aquatic ecosystems, discusses emerging conservation technologies, and highlights sustainable management approaches for protecting freshwater fish resources under changing environmental conditions.