Abstract
The objectives of the current study are to categorizing existing fish species diversity, abundance and conservation status with specific biodiversity losses of Nikli Haor located in Kishorgonj district in Northeastern part of Bangladesh. This haor is recognized for its fish resources and revenue for many fishermen. This study was conducted from June 2022 to July 2023. Data were collected monthly by field survey, focus group discussions (FGD), questionnaire interviews (QI) of fishermen, and secondary data collection from the Nikli Haor. A comprehensive inventory has shown the presence of 53 distinct fish species, which can be classified into 20 families and 8 orders. The Cypriniformes has been documented as the most predominant group in terms of both species richness and population abundance. In this study, a notable proportion of fish species, specifically 35.84%, are facing various levels of vulnerability. This includes 11.32% classified as vulnerable, 18.87% as endangered, and 5.66% as critically endangered. The study resulted diversity, evenness, and richness indices with values of 3.62, 0.79, and 7.27, respectively. Nonetheless, the abundance and diversity of fish species in the Nikli Haor are declining. As a result, the findings could be utilized to develop and implement action plans that will help in the long-term management of Haors.