A year-long research was conducted with a novel purpose for categorizing and documenting the existing fish diversity and abundance of Bamui beel in Jamalpur district located in Northeast part of Bangladesh, within a time frame from July 2022 to June 2023. A total of 46 fish species were identified that belonged to 18 taxonomical families and 8 orders. The most abundant family was Cyprinidae (25%). Among 46 species, 37% were commonly available (CA) and 11% were abun-dantly available (AA) in terms of biodiversity status. According to the global conservational sta-tus, around 74% were reported as least concerned (LC) whereas 4% were nearly threatened (NT). On the other hand, in consonance with the conservational status of Bangladesh 52% were least concerned (LC) and 11% were endangered (EN). Pielou’s evenness score in Bamui beel was the highest (0.247) in pre-monsoon and the lowest (0.213) in monsoon. Shannon-Weaver diversity index was ranged from 1.992 to 2.114, whereas Simpson’s dominance index value was a maxi-mum of 0.883 in pre-monsoon and a minimum of 0.852 in monsoon. The yearly fish production of the beel was 7.023 metric tons during experimental year. Besides this, small indigenous species (SIS) of fish dominated with 63.34% of the beel's species makeup. Nevertheless, the abundance and diversity of fish species are diminishing daily in this beel. For preserving the fish diversity of Bamui beel calls for the implementation of effective fishery management practices, vigilant monitoring to prevent overfishing, and a strong emphasis on raising awareness among fishermen.