The walking catfish Clarias magur (Hamilton, 1822) (magur) is an important catfish species inhabiting the Indian subcontinent. It is considered as a highly nutritious food fish and has the capability to walk to some distance, and survive a considerable period without water. Assembly, scaffolding and several rounds of iterations resulted in 3484 scaffolds covering ∼94% of estimated genome with 9.88 Mb largest scaffold, and N50 1.31 Mb. The genome possessed 23748 predicted protein encoding genes with annotation of 19,279 orthologous genes. A total of 166 orthologous groups represented by 222 genes were found to be unique for this species. The Computational Analysis of gene Family Evolution (CAFÉ) analysis revealed expansion of 207 gene families and 100 gene families have rapidly evolved. Genes specific to important environmental and terrestrial adaptation, viz. urea cycle, vision, locomotion, olfactory and vomeronasal receptors, immune system, anti-microbial properties, mucus, thermoregulation, osmoregulation, air-breathing, and detoxification etc. were identified and critically analyzed. The analysis clearly indicated that C. magur genome possessed several unique and duplicate genes similar to that of terrestrial or amphibians’ counterparts in comparison to other teleostean species. The genome information will be useful in conservation genetics, not only for this species but also be very helpful in such studies in other catfishes.
Growth, survival and production of endangered Indian butter catfish (Ompok bimaculatus) fingerlings were examined at different stocking densities. The experiment was conducted for 8 months in nine earthen ponds having an area of 0.03 ha each. 30-day-old fingerling, stocked at 40 000 ha À1 was designated as treatment-1 (T1), 50 000 ha À1 as treatment-2 (T2) and 60 000 ha À1 as treatment-3 (T3). At stocking, all fingerlings were of same age group with a mean length and weight of 3.36 AE 0.08 cm and weight of 0.83 AE 0.02 g respectively. Fish in all the treatments were fed with a mixture of rice bran (50%), mustard oil cake (30%), fish meal (19%) and vitamin-mineral premix (1%). Physicochemical parameters, plankton populations and soil parameters were at the optimum level for fish culture. Highest weight gain was observed in T1 and lowest in T3. Final length, weight and survival of fish also followed the same trend as weight gain. Highest specific growth rate was observed in T1 followed by T2 and T3. Feed conversion ratio was significantly lower in T1 followed by T2 and T3 in that order. Significantly higher amount of fish was produced in T1 than T2 and T3 respectively. Higher net benefit was obtained from T1 than from T2 and T3. Overall, the highest growth, survival and benefit of fish were obtained at a density of 40 000 fingerlings ha À1 . Hence, of the three stocking densities, 40 000 fingerlings ha À1 appears to be the most suitable stocking density for culturing of Indian butter catfish in grow-out system.
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