A decade-long scientific assessment by the Barrackpore-based ICAR–Central Inland Fisheries Research Institute (ICAR–CIFRI) — conducted under the government of India’s Namami Gange programme — has found that while the Ganga continues to sustain rich fish biodiversity, many species remain vulnerable.

The study, carried out between 2016 and 2025, documented 230 fish species across the Ganga basin.

Of these, 221 are native and nine exotic, underlining the ecological importance of the river system.

Also, nearly 10 per cent of the recorded species — 23 — fall under threatened categories of the Red List of the International Union for Conservation of Nature that lists vulnerability of species.

“The findings reflect the cumulative impact of multiple rejuvenation initiatives, including Namami Gange,” said Basanta Kumar Das, the director of ICAR–CIFRI.

“The findings also provide a strong scientific foundation for policy formulation, conservation planning and sustainable fisheries management in the Ganga basin,” he added.

Researchers identified the Cyprinidae family as the most dominant commercial group in the freshwater stretches of the Ganga.

This family, which includes Indian major carps and minnows, forms the backbone of inland fisheries and supports the livelihoods of thousands.

Sources in ICAR-CIFRI said that the historical data spanning more than 200 years reveal sharp fluctuations in fish diversity.

The first major scientific survey in 1822 recorded 271 species, reflecting a highly diverse ecosystem. However, rapid industrialisation, untreated sewage, habitat degradation, declining water quality and overfishing led to a steady decline.

By 1974, the number of recorded species fell to 207, dropping further to 172 in 1991. Fish diversity reached its lowest point in 1998, with just 110 species recorded.

“Against this backdrop, the current count of 230 species marks the strongest recovery in over five decades, thanks to river rejuvenation initiatives, improved fisheries management and habitat restoration under programmes such as Namami Gange,” said a source.

The assessment, which covered 33 tributaries and six floodplain wetlands across the Ganga basin, shows that. Uttar Pradesh emerged as the most diverse stretch, with Bijnor recording 109 species and Narora 93 species.

In Bengal, Farakka showed 85 species.

“Some other locations, including Behrampore, Frazerganj, Balagarh and Tribeni, showed moderate recovery, but lower estuarine stretches such as Diamond Harbour and Gadkhali continued to report lower diversity," the source added.

Experts noted that river ranching and stock enhancement played a major role in rebuilding fish populations.