The present study investigates the range extension of the endemic ornamental fish species Puntius halakkudiensis within the river ecosystems of Southern Kerala, India. Historically confined to specific river systems, this species has shown remarkable adaptability, expanding its habitat range. Ecological surveys were conducted to assess the distribution, habitat preferences, and population dynamics of P. halakkudiensis across various river systems in Southern Kerala. Our findings reveal significant range expansion, highlighting the importance of conserving and managing the habitat of this unique fish species. This research provides valuable insights into the dynamics of endemic fish species within a changing environment and underscores the need for sustainable conservation measures.