Eight different exotics (viz. Ctenopharyngodon idella, Hypophthalmicthys molitrix, Hypophthalmicthys nobilis, Cyprinus carpio var. communis, Cyprinus carpio var. specularis, Oreochromis niloticus, Clarias gariepinus and Pterygopliicthys disjunctivus) were recorded from all freshwater stretch of River Ganga.

The upper stretch (Harsil to Haridwar) was dominated by common carp viz. Cyprinus carpio var. communis (19.59%) and Cyprinus carpio var. specularis (13.61%). The increasing occurrence in the region might be due to natural recruitment and adaptation to lotic habitat. The middle stretch (Haridwar to Varanasi) was recorded highest abundance of Cyprinus carpio var. communis (1.46%), Oreochromis nloticus (2.01 %) and Clarias gariepinus (0.37 %) respectively. Abundance of other exotics like Ctenopharyngodon idella, Hypophthalmicthys molitrix, H. nobilis was found below 0.10 %.S ites like Kanpur, Prayagraj and Varanasi showed major abundance of common carp (7.31%; 16.49%;4.95%) and Tilapia (6.64%;7.36%;4.59%).

In the lower stretch (S 10-S17), dominance of common carp (Cyprinus carpio var. communis) and Tilapia (Oreochromis nloticus) was noticed at site Buxar only. Sporadic availability of other exotic species was noticed below Bhagalpur to Tribeni stretch of River Ganga. The distribution pattern of exotic fish species in the river denotes that, C. carpio, was found omnipresent in ten sampling sites holding considerable local level distribution (52.63 %) followed by C. idella (42.10 %)

However, Tilapia was confronted in seven sites with the distribution range of 36.84%. Reduced water flow, high organic loadings and water abstraction are the favourable hydrobiological conditions for the exotics to establish at faster rate in some of the stretch of river Ganga.