2.1 Description of study area The fish species diversity was recorded in Tahirpur Upazila, Sunamganj district in Bangladesh from January 2017 to December 2017. Sunamganj is a district that situated in the north eastern part of Bangladesh. There are 11 Upazilas in Sunamganj named Chattak, Jamalganj, Jagannathpur, Tahirpur, Dakshin Sunamganj, Derai, Shulla, Dowarabazar, Dharmapasha, Bishwambharpur and Sunamganj Sadar. Tahirpur is a upazila which is mostly known for the beauty of nature and large natural wetlands like haors and beels. The area of Tahirpur is 313.7 square kilometers. It contains 7 unions, 131 mouzas, 244 villages. It is located at 25.0917º N to 91.175º E. Meghalaya is situated in the northern part of Tahirpur and its eastern part is Biswambharpur upazila. Jamalganj is in Southern part and Dharmapasha is in western part of Tahirpur. The hilly areas of Meghalaya are the descent place of many rivers in Tahirpur.The area contains the unique wetland named haor. The second largest haor in Bangladesh named Tanguar haor is situated in the Tahirpur and Dharampasha upazila. The haor is well known for its aquatic biodiversity. The haor is a wetland ecosystem of Bangladesh which physically is about bowl shaped shallow depression. During monsoon, haor receives a large amount of runoff water from the hilly region of Meghalaya and become vast waterbody looks like sea. The popular haors in Tahirpur are Tanguar haor, Shanir haor, Matian haor, Karcha haor etc. There are also some rivers named Jadukata river, Patnai river, Bawlai river etc. which comes from the Meghalaya. There are also many beels, ponds, lakes in the area. The popular beels are hatirgatha, mohisergatha, kawer khal, teilla beel, matian beel, boro beel etc. The popular lake is Niladri lake which is situated in Takerghat have a great aesthetic value and great availability of fish biodiversity.
2.2 Data collection A field survey was done in the area. Before that an appropriate questionnaire was prepared and used for collecting data from villagers of the surrounding study area in Tahirpur upazila. Primary and secondary sources are considered to interpret during data collection. Primary data is about present status of fish biodiversity were collected by 100 questionnaire interviews. The fisherman of the area involved in fishing in Tanguar haor, Shanir haor, Matian haor, Patnai haor, Niladri lake, Jadukata river, Bawlai river and some other wetlands. The primary data collection was done by questionnaire interview and secondary data was was done to collect data. A total 15 focus group discussions were done to collect data where each group consisting 10 members. QI and FID’s were made in 15 villages and bazaars which are popular for fishing in Tahirpur named Badaghat Bazar, Balijuri Bazar, Sreepur Bazar, Bordal Bazar, Takerghat, Notunbazar, Ratansree, Sulemanpur Bazar, Lalghat Bazar, Kolagaon bazaar, Lawergorh Bazar, Anwarpur Bazar, Tahirpur Bazar, Matikata and Padabuka. The secondary information about the fish diversity are collected from the Fisheries Officer of Tahirpur Upazila, District Fisheries Officer of Sunamganj, local leaders, fish traders, NGO workers in the study area. The fish and prawn species were categorized into four groups on the basis of availability such as – Commonly Available (CA), Moderately Available (MA), Rarely Available (RA), Very rarely Available (VR). There are also some extinct fishes which are included. Finally, data were analyzed using Microsoft Office Excels 2010.