Published Paper Details:

Assam is the land of rivers and streams. Considering the very high ecological diversity of the water assets and the blessings of the river and stream network, most of the cities and towns development in this state occurred close to the rivers and streams. Species diversity is acknowledged as foremost trait of ecosystem functioning. Seasonal variation of fish assemblage structure with physico-chemical parameters in Langting stream, Dima Hasao district, Assam were studied based on survey and analysis, conducted during March 2021 to February 2022. During the four seasons each with three different stations were selected for data collection. Shannon diversity index, the Simpson index and Margalef diversity index have been used to access the diversity. To explore the fish assemblage structure, fish samples were collected in seasonal basis from three sites of the stream by using cast net and gill net. A total of 1335 individuals belonging to 5 orders, 20 genera, 12 families and 27 species were collected from the selected sites. 11 species out of total 27 species found in Langting river, belong to order Siluriformes followed by Cypriniformes (10), Perciformes (3), Synbranchiformes (2) and Beloniformes (1). The most abundant species was Nandus nandus. For the season-wise and station-wise diversity of fish, the topmost Shannon?s diversity index (3.25) during post-monsoon at station 1, Simpson index (0.98) in all seasons and stations, Margalef diversity index (7.03) during pre- monsoon at station:1were recorded. The CCA analysis showed that the fishes like Labeo cabsu (C6), Punitus sophore (C7), Punitus tict (C8), Bagarius bagarius (C14) and Anabus testudineus (C24) were found to be strongly correlated with Free Carbon dioxide, furthermore, species like Rita rita (C11), Ompak pabda (C15), Wallago attu (C17) and Europiichthys vacha (C18), showed negative correlation towards water temperature (WT), dissolved oxygen (DO), pH, Alkalinity and Turbidity. Present study could be accountable for further exploration of fish diversity, water parameters or other relevant topics in future. Imposing fisheries regulations to reduce human activities are inevitable to sustain multitudinous fisheries.