ABSTRACT
A study was conducted to be known the water qualities and richness of fisheries resources in Meghna river at Narsingdi region of Bangladesh during the period from December 2015 to February 2016. The water samples were collected from five different stations indicated as St-1 (Narsingdi launch ghat), St-2 (Hajipur), St-3 (Champa nagar), St-4 (Korimpur) and St-5 (Nazarpur) from the study zone under Narsingdi district.Fish samples were collected from three locations (St-2, St-3 and St-5) capturing by fishing net. A questionnaire survey was also performed in order to assess the impact of water quality degradation on the abundance of fishes in Meghna River. The result of the study showed that the temperature, EC, TDS, DO, BOD, pH and hardness of the Meghna river water were ranged from 19.1 to 19.6ºC, 525 to 714 µS/cm, 113 to 197.67 mg/l, 3.33 to 4.3 mg/l, 1.23 to 2.9 mg/l, 7.72 to 7.91 and 94 to 126 mg/l, respectively during the study period. The obtained results assured the desired quality of water in terms of above parameters except DO. The study identified a total of nine fish species under five orders and six families. Here Foli (Notopterus notopterus) considered as vulnerable accordingly IUCN (2000). It was also found that water quality degradation (33.75%) negatively influenced the abundance of fish species. Proper management and monitoring along with implementation of existing laws and regulations for industrial discharge of waste should be carried out to maintain the water quality of Meghna river so that the river can remain as a healthy ecosystem and habitat for fresh water fishes.

Key words: Meghna river, water quality, fish diversity, physicochemical parameters.

Introduction

Though water is the most valuable and vital resource for sustenance of life (Kumar et al., 2010), but susceptibility to pollution because of waste and wastewater accessibility (Ahmed et al., 2011). The surface water qualities of the rivers of Bangladesh are getting highly polluted day by day (DoE, 1992; Alam et al., 2007). In recent years, the river systems in Bangladesh have become more polluted as a consequence of rapid population growth, uncontrolled development on the riverbanks, urbanization, unplanned industrialization, and agricultural operations (Islam et al., 2015a).The pollution from industrial effluents and from agro chemicals into rivers has reached alarming levels; resulting in serious effects on aquatic organisms as well as fish species (Islam et al., 2014). Bangladesh has extensive water bodies that have a high potential for fisheries production. There are 260 indigenous freshwater species and 475 species of marine water fishes in Bangladesh (DoF, 2013). Recently fish is considered as one of the most endangered species in Bangladesh (IUCN, 1998). The population of natural fish species has declined considerably due to increased fishing pressure and various anthropogenic activities leading to siltation, aquatic pollution and loss of natural habitat for spawning and growth (Akhteruzzaman et al., 1998). The Meghna river flows over Narsingdi sadar upazila. It is one of the great sources of fishing and supports many people in their livelihood. Many settlements, towns and industries have sprung up on both the banks of the Meghna. In this aspect, the present study was an attempt to investigate the present status of water quality, fish biodiversity and to find out the major causes of water quality degradation of Meghna river which is being impacted on fisheries resources.

Materials and Methods
Study area: The study was conducted in the Meghna River at Narsingdi sadar upazilla of Narsingdi district (central Bangladesh), during the period from December 2015 to February 2016.The river is located