Five iso-nitrogenous (300 g kg )1 diet) purified diets with graded level of lipid at 40 (D-1), 60 (D-2), 80 (D-3), 100 (D-4) and 120 (D-5) g kg )1 diet were fed to Puntius gonionotus fingerlings for 90 days to determine their dietary lipid requirement. Two hundred and twenty-five fingerlings (average weight 2.34 ± 0.03 g) were equally distributed in five treatments in triplicate groups with 15 fish per replicate. Fifteen flow-through cement tanks of 100 L capacity with a flow rate of 0.5 L min )1 were used for rearing the fish. Specific growth rate (SGR), feed conversion ratio (FCR), nutrient digestibility, retention, digestive enzyme activity, RNA : DNA ratio and whole-body composition were considered as the response parameters with respect to dietary lipid levels. Maximum SGR and minimum FCR with highest RNA : DNA ratio, whole-body protein content and digestive enzyme activity was found in D-3 group fed with 80 g kg )1 diet lipid. Nutrient digestibility was similar in all the groups irrespective of the dietary lipid level. Maximum protein and energy retention was recorded at 80 g kg )1 dietary lipid fed group. However, from the second-order polynomial regression analysis, the maximum growth of P. gonionotus fingerlings was found at 96.9 g lipid kg )1 diet. KEY WORDS

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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.

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Asian seabass or barramundi (Lates calcarifer) is an important food fish with commercial value and a wide geographic distribution. Though some reports based on molecular and/or morphological data exist, a comprehensive effort to establish species identity across its range is lacking. In order to address this issue and especially to ascertain whether the widespread distribution has resulted in bifurcation of the species, we collected Asian seabass samples from various locations representing the Western and Eastern Coastline of India, Andaman and Nicobar Islands, Bangladesh and Australia. Samples from Malaysia, Indonesia, Thailand and Singapore were collected as part of a previous study. DNA sequence variations, including cytochrome c oxidase subunit 1 (COI), 16S rDNA and the highly variable D-loop (or control region), were examined to establish species delineation. Data from all the sequences analyzed concordantly point to the existence of at least two distinct species-one representing the Indian subcontinent plus Myanmar, and a second, representing Southeast Asia (Singapore, Malaysia, Thailand and Indonesia) plus Northern Australia. These data are useful for conservation ecology, aquaculture management, for establishing the extent of genetic diversity in the Asian seabass and implementing selective breeding programs for members of this species complex.