“Ichthyofaunal diversity" refers to the variety of fish species within a particular region or ecosystem. It encompasses the different species, their abundance, and the overall ecological balance within aquatic environments at munneruriver . Ichthyofaunal diversity plays a crucial role in maintaining the balance of aquatic ecosystems. Fish species contribute to nutrient cycling, control populations of prey species, and serve as indicators of environmental health.Species ranges may shift, leading to altered community compositions and potential loss of endemic species. Conservation strategies need to consider the long-term effects of climate change on ichthyofaunal diversity. This study was conducted in the munneru river from November 2022 to march 2024 the fish species are collected monthly with the help of local fishermen. in our study area we identified around 80 Fish species following 09 orders & 20 Families.