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Studies were undertaken to identify genetic relationship and diversity of Clarias batrachus L. populations collected from hatchery and wild stocks through random amplified polymorphic DNA (RAPD). 16 decamer primers were used for screening, out of which five produced amplicons. A total of 1376 RAPD bands ranging from 0.2 to 1.36 kb were amplified using five selected primers. The number of amplification products produced by a primer ranged from as low as three to a maximum of 18, with an average of 16 bands per primer. 8.1 to 13.71 polymorphic bands per primer were amplified. The polymorphic bands in these populations ranged from 56.4 to 59.6%. Polymorphic bands per lane within populations ranged from 4.88 to 5.3%. The similarity within the population from wild varied from 0.40 to 0.83 with a mean ± SE of 0.57 ± 0.08. The Jaccard's similarity coefficient ranged from 0 to 0.27. At 0.06 similarity coefficient, two major clusters were formed, which indicates that the genotypes belonging to same clusters were genetically similar and those belonging to different clusters were dissimilar. Significant (P < 0.05) population differentiation indicated some degree of intra-and inters-population genetic variations in two populations of catfish. This might be due to difference in habitat and breeding strategies between the two populations.

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Biotechnological research and development are moving at a very fast pace. The application of biotechnology in the fisheries sector is a neoteric practice. Nevertheless, it is a promising area to enhance fish production. Efficacy of exogenous nutrizymes in fish feed is being reinvestigated in the present time. A feeding experiment of 90 days was conducted to assess the efficacy of exogenous nutrizyme supplement diet on weight gain and growth performance of Labeo rohita fingerlings. Three supplementary diets (D1, D2 and D3) were prepared containing 30±0.6% crude protein, 4.8±2% crude fat and 11.6±0.2% crude fibre. Experimental diets D1, D2 and D3 were supplemented with papain at the level of 5, 10 and 12 g per kg of feed respectively. Feeding was done at the rate of 5%, twice a day. Rearing of fingerlings on diet D2 resulted in better growth of L. rohita fingerlings compared to those with the experimental diet, D3 and D1 followed by control diet D0 which was without any supplementation. Comparison of growth performance was done on basis of growth rate, nutrient digestibility, gross protein retention (GPR), feed conversion ratio (FCR), protein efficiency ratio (PER) apparent net protein utilization (ANPU) and survival percent.

The present study was undertaken in order to standardise the stocking density values of carps fishes for sustainable fisheries development in mid hills and enhancing the fish production. The paper deals with growth performance of 3 exotic fish species in low stocking density i.e. 3 fish/m3 over high stocking density of 5 fish/m3 and 10 fish/m3 in the control pond. The net production was 12.6% higher with stocking density of 3 fish/m3. Among the both tested density, the combination of 30: 40: 30 was superior (45.6%) in terms of growth and production in comparison to the other combinations and control. In present study, the highest production as 57.13kg/100m2 (5713 kg/ha.) was achieved in the stocking ratio of 30:40:30 with stocking density of 3 fish/m3. It is 4.7% higher of the combination of 40:30:30 and 4% higher than the combination of 30: 30: 40. It is 12.6% higher than the stocking density of 5 fish/m3 and 48.5% higher than the stocking density of 10 fish /m3. The growth pattern reflected the slow growth during the winter months, reflected the direct negative effect of water temperature on the growth. The production level of existing practice of the farmers may be enhanced up to 1.5 times with proper stocking density i.e. 3 fish/m3 and perfect species combination i.e. 30: 40: 30 for silver carp, grass carp and common carp respectively.

Over the period of time, patent filing in India has gone up significantly. However, no enough evidence is found in the literature about the quality or value of patented invention in the Indian context. To assess this question, we examine the patent renewal length (survival of patent) as a proxy of patent value for five different technology classes. This study uses the renewal information of firm‐level patents applied during January 1, 1995, and December 31, 2005, which were eventually granted. The data provided by Indian Patent Office consists of 2,025 resident patents assigned to 266 firms (foreign subsidiary firms and domestic firms). The survival analysis is carried out via Kaplan–Meier estimation and Cox proportional hazard regression. The outcomes of this study suggest that the survival length of patents significantly depends on their technological scope and inventor size. Moreover, the patents of the firms taking tax credit benefits exhibit lower survival rates as compared with patents of remaining firms. The study also finds that the patents filed by foreign firms with Department of Scientific and Industrial Research affiliation survive longer. Among different technological categories, electrical and mechanical patents are found to be more valuable compared with instrument patents.