UTTAR PRADESH JOURNAL OF ZOOLOGY

Fish diversity is often used to measure the health of the biological system of lotic and lentic ecosystems. But habitat loss and environmental degradation cause a rapid decline in biological diversity in aquatic ecosystems, which is a critical challenge to conserve the fish germplasm in natural habitats for the modern era. Maharashtra, India's second-most populous state, encompasses one of the most hydrologically diverse landscapes on the Indian subcontinent, spanning portions of the Western Ghats biodiversity hotspot, the Deccan Plateau, and the Konkan coastal plain. These physiographic zones drain into multiple major river systems—including the Godavari, Krishna, Bhima, Tapi, and numerous shorter Konkan rivers—collectively supporting a rich but incompletely documented assemblage of freshwater fishes. The Western Ghats section of Maharashtra harbours numerous endemic taxa, many of which face elevated extinction risk from intensifying anthropogenic pressures. This review critically synthesises the available literature on freshwater fish diversity in Maharashtra, examining patterns of species richness and endemism across the state's principal river basins, the taxonomy and functional ecology of dominant ichthyofaunal groups, and the multifaceted threats confronting aquatic biodiversity. The literature assembled for this review was identified through systematic searching of the following electronic databases and repositories: Web of Science, Scopus, Google Scholar, PubMed, the Zoological Record, BIOSIS Previews, the Catalogue of Life, the IUCN Red List database, and the Biodiversity Heritage Library. Particular attention is directed to the cumulative impacts of hydrological alteration through dam construction, diffuse and point-source pollution, the proliferation of invasive alien fishes, overexploitation, land-use change, and the emerging challenges posed by climate change. The adequacy of the existing conservation and regulatory framework is evaluated, and significant research lacunae that currently impede informed management are identified. Freshwater fish inventories for Maharashtra remain incomplete relative to the state's biodiversity potential, and longitudinal monitoring of population trends is largely absent. Strengthening systematic ichthyological surveys, implementing environmental flow frameworks for impounded rivers, applying landscape-level conservation planning, improving regulatory enforcement, and integrating local ecological knowledge are identified as priorities for ensuring the long-term persistence of freshwater fish diversity in one of peninsular India's most significant biodiversity regions.