Summary In this study the intraspecific variation of wild Labeo rohita was investigated on the basis of morphometric characters using the truss network system constructed from the fish body. Altogether 435 fish samples were collected from six drainages of the Ganga basin in India. Data were subjected to principal component analysis, discriminant function analysis and univariate analysis of variance. The first principal component (PC1) explained 47.88% of the total variation, while PC2 and PC3 explained 17.22 and 8.33%, respectively. The step‐wise discriminant function analysis retained three variables that significantly discriminated the populations. Using these variables, 62.3% of the original groups were classified into their correct samples and 53.1% of the cross‐validated groups omitting one procedure were classified into their correct samples. Misclassification was higher for samples from the River Gomti (28.6%). Of the total of 31 transformed truss measurements, 30 exhibited significant differences among populations. These findings indicate the presence of six different stocks of L. rohita in the Ganga basin.

Length-weight relationships (LWRs) were evaluated for Badis badis (n = 25), Sperata seenghala (n = 26), Labeo gonius (n = 34), Rasbora rasbora (n = 30), Bagarius bagarius (n = 24), Gagata cenia (n = 27), Glyptothorax stoliczkae (n = 24) and Channa orientalis (n = 28) from the Ravi River tributary in North India. Altogether 218 samples of eight species were obtained between May and November 2014 using cast nets and gill nets. LWRs for these species were unknown to FishBase, and new maximum lengths were recorded for two of these species.

We investigated intraspecific variation of the Snowtrout, Schizothorax richardsonii on the basis of morphometric characters. Altogether, 217 specimens were collected from four rivers in the Western and Central Indian Himalaya. A truss network was constructed by interconnecting 14 landmarks to yield 31 distance variables that were extracted from digital images of specimens using tpsDig2 and PAST software. Transformed truss measurements were subjected to univariate analysis of variance, factor analysis and discriminant analysis. All variables exhibited significant differences between the populations. Altogether 86.6% of the specimens were classified into their original populations (82.9 % under a ‘leave-one-out’ procedure). With factor analysis measurements of the head region, the middle portion and the caudal region had high loadings on the on first and second axis. The results indicated that S. richardsonii has significant phenotypic heterogeneity between the Western and Central Indian Himalayas. We hypothesize that the marked interspecific variation in S. richardsonii is the result of local ecological conditions.

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