Diseased Anabas testudineus exhibiting signs of tail-rot and ulcerations on body were collected from a fish farm in Assam, India during the winter season (November 2018 to January 2019). Swabs from the infected body parts were streaked on sterilized nutrient agar. Two dominant bacterial colonies were obtained, which were then isolated and labelled as AM-31 and AM-05. Standard biochemical characterisation and 16S rRNA and rpoB gene sequencing identified AM-31 isolate as Aeromonas hydrophila and AM-05 as Aeromonas jandaei. Symptoms similar to that of natural infection were observed on re-infecting both bacteria to disease-free A. testudineus, which confirmed their virulence. LC50 was determined at 1.3 × 104 (A. hydrophila) and 2.5 × 104 (A. jandaei) CFU per fish in intraperitoneal injection. Further, PCR amplification of specific genes responsible for virulence (aerolysin and enterotoxin) confirmed pathogenicity of both bacteria. Histopathology of kidney and liver in the experimentally-infected fishes revealed haemorrhage, tubular degeneration and vacuolation. Antibiotic profiles were also assessed for both bacteria. To the best of our knowledge, the present work is a first report on the mortality of farmed climbing perch naturally-infected by A. hydrophila as well as A. jandaei, with no records of pathogenicity of the latter in this fish.

Length-weight relationships (LWRs) are presented for two fish species: Schistura fasciata Vishwanath, 2011 and Schistura reticulofasciata (Singh and Bănărescu, 1982), sampled from the Simsang River in Meghalaya, India. Fishes were caught seasonally from January to December 2015, with cast nets (10-15 mm mesh size) and electrofishing devices. The b values in the LWRs were determined as 3.09 for S. fasciata and 3.318 for S. reticulofasciata. | 1037TALUKDAR eT AL. a digital slide calliper (Mitutoyo, CD-8″CSX) to the nearest 0.01 mm and the values converted into centimetres. Body weight was taken with an electronic balance (TP 303, Denver Instrument, Germany) to the nearest 0.01 g. The relationships between total length and weight were determined through linear-regression equation of log TW = log a + b log TL. Log-log plots within species were done to remove outliers using SPSS 17.0 (SPSS Inc. Ltd., Sacramento, California). The 95% confidence limits for b (CL 95%) were calculated to determine if the hypothetical value fell between these limits (Froese, 2006). | RESULTSDescriptive statistics and estimated LWR parameters for the two fish species from Simsang River are shown in Table 1. A total of 200 specimens (S. fasciata = 69, S. reticulofasciata = 131) were used to estimate the LWRs. | DISCUSSIONNo LWR data are available for either of the two species in FishBase (Froese & Pauly, 2016). The 'b' values for S. fasciata and S. reticulofasciata (calculated as 3.09 and 3.318, respectively) were within the expected range of 2.5-3.5 (Froese, 2006). Comparing the results for the two species against the Bayesian approach, parameter 'a' was found to be within the expected range for elongated fish species (i.e. 0.0018-0.00842 95% range of a) (Froese, Thorson, & Reyes, 2013).

Summary Length‐Weight relationships (LWRs) for three Cyprinids (Chela cachius, Devario devario and Securicula gora) collected seasonally from May 2016 to January 2017 along the lower Brahmaputra drainage in Assam (Northeast India), using fishing gears [cast nets: 2.5 m, 10–15 mm mesh size; gillnets: 30 × 0.9 m, 18–20 mm mesh size], were estimated. The ‘b’ values of the LWR estimates ranged from 3.39 for C.  cachius, 3.14 for D.  devario, and 2.97 for S.  gora respectively.

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Summary The present study describes the length–weight relationships (LWRs) for three ornamental hill stream fish species from the Manas River in Assam, India, namely, Barilius bendelisis (Hamilton, 1807), Barilius shacra (Hamilton, 1822), and Barilius barna (Hamilton, 1822). Fishes were collected on a monthly basis from March 2015 to February 2016 with cast nets (270 cm, 1.2 cm) and gillnets (7,500 × 130 cm, 5 cm). This is the first information on LWR data for two of the species.