This study aimed to investigate the fish diversity in relation to environmental parameters in the mining-impacted area of the Ganga River in India. Four zones, i.e. Zone A, Zone B, Zone C and Zone D, were selected for the targeted study, viz. Bairaagi camp, Shyampur Kangri, Bisanpur village and Bhogpur village. Zone A was a non-mining area and hence termed as reference zone, while the remaining zones were areas where river bed mining was carried out. Sampling was carried out twice a month for environmental parameters and once a month for fishes. Overall sixteen environmental parameters were studied and analysed using one-way ANOVA. A total of 5299 individuals associated with 13 families were collected and analysed using two indices, namely the Shannon–Wiener diversity index (H′) and total number of individuals. In addition, canonical correspondence analysis revealed that selected environmental parameters such as water velocity, water temperature, water depth, boulders, sand, gravel, turbidity and dissolved oxygen had significant relationships with fish assemblage. The result showed that more fish were found in the non-mining-impacted zones than in the mining-impacted zones. However, it was found that mining of river bed materials disturbed the environmental parameters and this has affected the fish community. © 2022, The Author(s), under exclusive licence to The National Academy of Sciences, India.