Summary Length–weight relationships for six small indigenous fish species, namely: Trichogaster chuna (Hamilton, 1822), Trichogaster lalius (Hamilton, 1822), Trichogaster fasciata Bloch & Schneider, 1801, Chanda nama Hamilton, 1822, Parambassis lala (Hamilton, 1822), and Macrognathus aral (Bloch & Schneider, 1801) were studied for the first time from Deepor beel, a Ramsar site (589 ha water spread area) located in Assam, India. A total of 617 fish specimens were collected for the present study on a monthly basis from February to August in 2016 from landing centres adjoining the beel. In the present study, b value ranges from 2.778 to 3.215, which is within the normal range. The LWRs for these six fish species from Deepor beel had not yet been reported for FishBase.

Deepor beel (Latitude: 26°05?26??N to 26°09?26?? N; Longitude: 90°36' E to 90°41?25?? E) located in Kamrup district, Assam is a large (water spread area of 589 ha) natural wetland and a Ramsar site of international importance (Site number 1207 declared in 2002) having enormous biological and environmental importance. The wetland receives water from surface run-off as well as from two hill streams (Basistha and Kalamoni) and drains into River Brahmaputra, through a small rivulet (Khanajan). The beel supports a number of endemic endangered and threatened animals and plants that are included under IUCN red-list. Past studies indicated the occurrence of 67 fin-fish species in the beel. In a recent survey conducted by us, the beel Bangana dero (Synonyms: Cyprinus dero/ Labeo dero), a cyprinid fish, was collected for the first time from the beel. We collected as many as 28 specimens of B. dero from the beel during October 2016. The total length of the reported specimens ranged from 8.77 - 10.14 cm and weight ranged from 6.74 - 10.61 g. The length-weight relationship of the species was worked out as W = 0.074*L2.103. B. dero reportedly inhabits upland rivers, torrential hill-streams; adults migrate to warm downstream regions during the winter season (December-February). Thus, the occurrence of this species in Deepor beel indicates its possible downstream migration from one or both the feeder rivers (Basistha and Kalamoni) or migration from Brahmaputra River through its connecting channel.

Abstract:The minor carp, Aspidoparia morar is a benthopelagic fish belonging to the sub-family Danioninae under the family Cyprinidae. It has emerged as the single most dominant species in the river Brahmaputra in Assam. In the present study, 240 specimens were collected from Guwahati and Tezpur in the Brahmaputra River and Silchar in the Barak River to investigate the morphometric and meristic variation among the populations. For this a total of 20 morphometric traits and 11 meristic traits were studied. The mean lengths for most of the morphometric traits were higher for the Barak River except eye diameter, inter orbital length and anal fin length which were significantly higher on the Brahmaputra River, while the post orbital length and pelvic fin length were found to be almost equal. The regressions of standard length with all the morphometric traits except pelvic fin length, pelvic fin base, pectoral fin length, dorsal fin length, anal fin length, pre orbital length, post orbital length, inter orbital length and eye diameter showed significant variation between the rivers. Two meristic traits viz. branched rays in anal fin and gill rakers on the first gill arch also showed significant variation in the samples of the rivers.

Deepor Beel is a prominent floodplain wetland and a Ramsar site of northeastern (NE) India (Ramsar site no. 1207) covering a 40.14 km2 area and connected to River Brahmaputra. It provides numerous economic (e.g., livelihood and nutritional security) and ecological benefits (e.g. moderation of floods, groundwater recharge, repository of biodiversity) to the locality and its people. Deepor Beel was declared a Wildlife Sanctuary in 1989 and the area covered by the perennial water spread (10.1 km2) was subsequently designated as a Bird Sanctuary by the Government of Assam in 2009. The present paper provides an overview of the rich floral and faunal diversity of the wetland, including aquatic macrophytes (58 species), diatoms (65), zooplankton (171), bryozoans (5), molluscs (15), aquatic insects (55), prawns (3), crabs (2), finfish (68), amphibians (11), reptiles (33), birds (234) and mammals (24), in addition to the beel's limno-chemistry as well its conservation threats and suggested strategies. The wetland supports 18 globally threatened vertebrate species. Eleven bird species occurring in the wetland (Aythya baeri, A. nyroca, Leptoptilos dubius, L. javanicus, Ephippiorhynchus asiaticus, Gyps bengalensis, G. tenuirostris, Haliaeetus leucogaster, Pelecanus philippensis, Sarcogyps calvus, Threskiornis melanocephalus) have been included in the IUCN Red List of Threatened Species. Finfishes reported from the wetland declined from 67 species in 1999 to 64 between 2016 and 2018, which is a matter of concern. According to available information on limno-chemistry, the waters of the wetland have remained within the favorable range of water quality for fish production. Major threats faced by the wetland (e.g. pollution, encroachment, natural processes, etc.) and possible conservation strategies (e.g. control of aquatic pollution, prevention/ control of siltation, enacting and enforcing appropriate legislation, and other strategies) are outlined.