Invasive Potential of Nile Tilapia, Oreochromis Niloticus (Linnaeus, 1758) From the Tributary of the Ganga River, Central India

Abstract

The natural fishery or wild stock of fishes especially fresh water in India is significantly declining due to manmade stressors. The invasion of fishes and size composition are an essential component of stream, river and other large water bodies ecosystem and represents an evident of structure, function, depth and health of stream/river. During study period 683 specimens of Oreochromis niloticus were collected from February 2019 to January 2020 in Sirsa fish landing centre from the lower stretch of the Tons river at Prayagraj, Uttar Pradesh, India. Size composition of fishes was varied from 82 to 463 mm (total length). The maximum total length of O. niloticus in the catches indicated that its increasing colonisation success in the river Tons. Size composition of fishes was also indicated that the stock of O. niloticus in the Tons river was in healthy condition. The 231-260 mm size group was most dominated (15.67%) compared to 261-290 mm (12.44%) and 291-320 mm (11.71%) in the total exploited stock. The middle size group was maximum exploited with 51.24% from the Tons river at Prayagraj. Higher size group contributed sizeable proportion with 25.04% in the exploited stock. The exploitation pattern was unsystematic in higher size group due to contribution of higher proportion. Current exploitation pattern is unsystematic but O. niloticus is powerfully invaded from the lower stretch of the Tons river at Prayagraj.