SummaryTen indigenous freshwater fish species belonging to nine genera and seven families were collected from Gandak River, Bihar, India during December, 2014 to September, 2016. Fishes were caught using Cast nets, Gill nets, Drag nets with mesh size of 15-20 mm, 25-30 mm and 5-10 mm respectively along with Traps. Sampling was done during dry and wet seasons and a total of 682 fish were collected for analysis of their Length-Weight Relationships (LWRs). Analyses included seven species for which no previous LWRs information were available in FishBase, and new maximum lengths were recorded for three species.

SummaryLength-weight relationships (LWRs) for five indigenous fish species under five genera and two families, namely Cyprinion semiplotum (McClelland, 1839), Barilius barna (Hamilton, 1822), Barilius barila (Hamilton, 1822), Gagata sexualis Tilak, 1970 and Pseudolaguvia shawi (Hora, 1921) were studied from Torsa River in West Bengal, India.Sampling was done at quarterly intervals from November, 2015 to December, 2016 and a total of 701 fish specimens were collected using cast nets (mesh size of 15-20 mm), gill nets (mesh size 20-35 mm) and bamboo traps. In the present study, b value ranges from 2.686 to 3.268. LWRs for these fish species (except P. shawi) have not been reported in FishBase. A new maximum length has been recorded for P. Shawi and G. sexualis. The relative condition factor (Kn) values was found to range from 1.004 to 1.028.

Summary Present study provides length–weight relationships (LWRs) and length–length relationships (LLRs) of eight fish species from river Ganga, India. Specimens were sampled from gill nets (mesh, 22–120 mm), cast nets (mesh, 12–14 mm), and seine nets (mesh, 12 mm) on quarterly basis from September 2016 to September 2017 within the river stretch from Buxar (25°33′43.90″N and 83°56′3.10″E) to Freserganj (21°35′40.58″N and 88°15′28.92″E). The b value ranged from 2.86 (Otolithoides pama) to 3.08 (Polynemus paradiseus), whereas a value ranged from 0.004 (P. paradiseus) to 0.016 (Rita rita). Both relationships (LWRs and LLRs) were found to be highly correlated (p < .001). This study provides first report on LWR for Amblyceps mangois and Osteobrama cotio, whereas new maximum length recorded for Macrognathus pancalus. Furthermore, the estimate of R. rita should be considered as tentative because of the limited size range in the study.

No abstract

For the study of length-weight relationship, morphometric and meristic characters, a total of 711 specimens (196 male and 515 female) of the Gangetic ailia, Ailia coila (Hamilton, 1822) were collected from Uzanbazar and Dhubri landing centres of river Brahmaputra, Assam during September 2013 to April 2014. The length and weight of males ranged from 66 to 154 mm and 1.218 to 20.5309 grespectively and that of females ranged from 66 to 161 mm and 1.4344 to18.2907 g respectively. The length-weight relationship was established as W = 0.002773 L 3.189306 and W = 0.005794 2.86234 for male and female, respectively. The analysis of covariance showed significant difference in ‘b’ values between sexes and student ‘t’ test indicated positive allometric growth for male and isometric growth for female. The morphometric characters were compared; showed maximum co-efficient of correlation (r) in standard and pre-dorsal length (0.98) while lowest was observed in mandibular barbel length (0.69) against the total length. Based on the study of meristic traits, the fin formula can be written as B6, P12-15, V5-6, C14-18, A61-75, GR17-24. The minor variations in meristic and morphometric characters could be attributed to genetic components and difference in geographical and environmental parameters like temperature and food availability. The study will helpful in identification of stock and stock-specific management strategies of this species in river Brahmaputra, Assam.