Ganga fish diversity under growing threat: Study
Kolkata: A decade-long scientific assessment by the ICAR–Central Inland Fisheries Research Institute (ICAR–CIFRI), Barrackpore, under the Namami Gange Programme has highlighted the rich but increasingly vulnerable fish diversity of the River Ganga.
The study, conducted between 2016 and 2025, documented 230 fish species, including 221 native and nine non-native (exotic) species, underscoring the river’s ecological significance. Around 10 per cent of the recorded species fall under threatened categories of the IUCN Red List, pointing to growing conservation concerns.
Cyprinidae emerged as the most dominant and commercially important fish family across freshwater stretches, represented mainly by major carps and minnows that sustain inland fisheries and the livelihoods of river-dependent communities.
Marked spatial variation in species richness was recorded along the river. Bijnor in Uttar Pradesh registered the highest diversity with 109 species, followed by Narora (93), Farakka (85) and Prayagraj (85).
In the estuarine zone, a distinct brackish-water assemblage was observed, with Fraserganj recording the highest estuarine diversity at 70 species. Tehri and Haridwar reported the highest abundance of threatened species.
Food fishes accounted for nearly 65 per cent of the total diversity, reaffirming the Ganga’s role in regional food and nutritional security. Ornamental fishes made up about 31 per cent, while sport fishes and species of lower economic importance constituted the remaining four per cent. The presence of nine exotic species, notably common carp (Cyprinus carpio) and tilapia (Oreochromis spp.), was also recorded. Their increasing dominance has raised ecological concerns due to potential competition with native species and habitat alteration.
Ecologically significant species such as mahseer (Tor putitora) and snow trout (Schizothorax richardsonii) were largely confined to the hilly and upper reaches, while hilsa (Tenualosa ilisha), a flagship and high-value species, dominated the lower and estuarine stretches.
Despite this biodiversity, the study reported a decline in fish landings and overall diversity, driven by pollution, over-exploitation, habitat degradation and illegal, poison-based fishing practices.
“The findings provide a robust scientific foundation for evidence-based policymaking, conservation planning and sustainable fisheries management,” said Basanta Kumar Das, director, ICAR–CIFRI.
