Assessment of fish fauna in relation to biodiversity indices of Chalan Beel, Bangladesh

The research was carried out to enlist the fish species diversity along with diversity indices of existing fish species of Chalan Beel, Bangladesh. During the study, a total of 78 fish species including 69 native and 9 exotic fish species were recorded belonging 10 orders and 26 families. The values of Shannon-Weiner diversity index (H') indicated a good spread of fish population in Chalan Beel although the number of species was not found satisfactory. The degradation of water quality due to domestic discharges, jute rotting, excessive usage of agro-chemicals, indiscriminate fishing activity etc. were revealed as the causes of declining the fish diversity of this Beel. The Margalef’s richness index (d) expressed the species richness of Chalan Beel that started in July by joining new fish population with the existing fish species and reached gradually highest in November after breeding. Pielou’s index (J) showed the equal distribution pattern of fish species throughout the sampling area indicating a stable but incompatible habitat for existing fish species. The assessment of the study revealed the number of species was not found in expected level in view of the overall fish biodiversity of the country. Considering the observations, it is recommended for stopping water pollution, ensuring normal water flow and developing awareness of fishermen to retrieve the fish diversity of the study area. Besides, an inclusive management and conservation scheme is crying need for the Beel fishery to enrich the fish species diversity of the Chalan Beel as well as the country.