Morphometric characteristics, length-weight relationships (LWRs), and condition factors (K) were studied for five indigenous fish species belonging to five different families (Barilius barila Hamilton, Cirrhinus reba Hamilton, Chanda nama Hamilton, Mystus bleekeri Day, and Clupisoma garua Hamilton), from the River Ganga in Bihar, India. A total of 557 fish individuals were collected seasonally from September 2021 to August 2022 using a monofilament drift gill net and a conical trap net Khairel jal. In morphometric analysis, the highest degree of correlation was observed between the total length and the standard length for all species (except C. garua). The estimated exponent value b varies from 2.920 to 3.214, where the slopes of regression lines among the species have significant differences ( p < 0.0001 ). The b value indicated that three species (B. barila, C. nama, and C. garua) follow positive allometric growth, whereas M. bleekeri shows isometric growth and C. reba exhibits negative allometric growth. The condition factor value for these fishes ranged from 0.67 to 0.98, which indicated that the population of C. reba was robust compared to all other species ( p < 0.0001 ). A new maximum length (146.8 mm) was obtained for B. barila from India. The present study gives baseline biological information on five commercially important indigenous fish species found in the River Ganga, Bihar. As the population of these species has been dwindling in recent times, these data will be important for the conservation and sustainable utilization of these important species in the long run.

The contribution of aquaculture and fisheries to Gross Domestic Product (GDP) is considered as one of the most important indicators for assessing the economic performance of the country. A large section of Bihar’s population relies on agriculture, animal husbandry, and fishing for their livelihood. The fisheries sector plays a critical role in ensuring nutritional security and creating employments. The culture and consumption of fish therefore has important implications for national income and food security. Bihar’s entire fish output in 2019 was estimated 0.64 mt, contributing 1.5% of the State’s total Gross Domestic Product (SGDP). However, the occurrence of annual saga in terms of floods and drought, rather than lack of recent advancement in aquaculture are the major challenges for the development of aquaculture in Bihar. Despite the fact that the state’s momentum in aquaculture over the last decade propelled it to fourth place in inland fish production and sixth place in freshwater seed production in India. The substantial investments in fisheries sector in the State can improve the income of farmers. The State’s aquaculture production can be further enhanced by harnessing the bestowed fishery resources at a sustainable level with approaches for acceleration in fish production such as promotion of aquaculture in wetlands, species and technological diversification for aquaculture, extension of improved aquaculture technology, realization the scope of integrated fish farming, establishing of fish hatchery, assembling of fish market and supply chain and propagation of ornamental fish activities.