The study was conducted to identify the present status of fish diversity in Soma Nadi Jalmohal of Sunamganj for a period of 11 months from June 2013 to April 2014. The study was done by questionnaire interviews (QI) of fishers, focus group discussions (FGD), key informant interviews (KII) and secondary data collection. A total of 56 species of fishes including prawn species belonging to 21 families were recorded from the jalmohal where Cyprinidae was the most dominant family contributing 16 species. The present availability status of fish species was remarked in three categories and obtained as 26 commonly available (47%), 18 moderately available (32%) and 12 rarely available species (21%). Among 56 available species, 8 species of carps, 12 species of catfishes, 9 species of barbs and minnows, 4 species of snakeheads, 4 species of eels, 10 species of perches, 3 species of loaches and other miscellaneous 6 species including 3 species of prawns were listed. The highest diversified group was catfishes (21.43%). Of 54 threatened fish species listed by IUCN (2000), only 20 species were found during the study period where 7 species were commonly available, 9 species were moderately available and 4 species were rarely available in the study area. The results of the study is implying that fish diversity of the jalmohal have been declining gradually due to some manmade and natural causes such as dewatering, sedimentation, overfishing, use of illegal fishing gears, catching of brood fishes etc. Community based fisheries management, use of appropriate fishing gears, sanctuary establishment and management, implementation of fish laws and regulations, fingerling stocking and dredging of beels and canals can play a great role in conserving fish diversity.