Assessing the Impact of Invasive Nile Tilapia (Oreochromis niloticus Linnaeus, 1758) and African Catfish (Clarias gariepinus Burchell, 1822) on Commercial Carp Fish Production in Selected Water Bodies of Wanaparthy District, Telangana, India

Abstract

The exotic fishes introduced into India for different purposes and some species has become invasive in inland waters. The spread of invasive fish is primarily driven by unauthorized aquaculture escaping into open waters. Nile tilapia, Oreochromis niloticus and African catfish, Clarias gariepinus once introduced in India have now established themselves in open water bodies as invasive species. The present study deals with the possible impacts of spread of African catfish and Nile tilapia into five selected water bodies i.e., Parameshwara tank, Apparala tank, Ooracheruvu tank, Ramasamudram tank and Gopaldinne reservoir in Wanaparthy district. The study was conducted from January 2023 to December 2025 to observe the impact of the above mentioned two invasive species on cultured commercial carp fish species. Data of Nile tilapia, African catfish, and other major commercial cultured carp fish catching were taken from the harvesting of the selected water bodies. The fish catch structure at the landing center was analyzed by direct observation of catches, graded as size-wise and species-wise with the help of local fishers. Results showed that commercial carp fish production was adversely affected by high density and abundance African catfish and Nile tilapia with established populations significantly and dominated over the cultured carp fish species during successive years. The present study recorded high Abundance Index (AI) 0.57 for tilapia, followed by 0.37 for carps and 0.06 for African catfish during 2023-2025. These results provide evidence of invasion success of the Nile tilapia and African catfish by adapting to the local environment for successful breeding. Results confirmed the   correlation between the reduced catches of cultured carp fish production and the high abundance of Nile tilapia and African catfish. Thus, appropriate actions must be initiated for effective planning in terms of native commercial carp fish production. The data generated in the present study will help in realizing the serious threat from dominant species to native ones.