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The clariid catfish, Clarias batrachus commonly known as Magur, has declined drastically from natural habitats in India during the last decade. This fish is highly preferred fish by Indian consumers and has high market demand. As a result traders often substitute C. batrachus with a morphologically similar but supposedly banned exotic catfish, C. gariepinus, in India. This study uses rigorous morphological comparisons confirmed by DNA barcode analysis to examine the level of substitution of C. batracus by C. gariepinus in India. Our results indicate that up to 99% (in many cases) of the market samples sold as Magur or C. batrachus were in fact C. gariepinus.

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Freshwater systems are among the habitats most sensitive to environmental changes and human interference. The increasing needs in India for supplies of both fresh water and fish as a food source under the pressure of a rapidly growing population mandate identification of ways to conserve natural resources while meeting these human needs. Dams provide a partial solution for both water and food fish supplies, especially in monsoonal areas, although disruption of natural fish habitats may offset these benefits. To examine this phenomenon, the Godavari River basin in India was sampled at 32 sites, and the effects dams might have on fish species assemblages and distribution at these sites were analysed. Although the river basin was rich in species, their representation and distribution was fragmented. The surveyed fish fauna included 114 species that were classified into 12 orders. Cyprinids dominated the fauna. Few introduced and cultured species were widely distributed in the river. Some native species were barely captured, suggesting they might be at risk of loss. The presence of the Godavari dams, as has been the case elsewhere, does appear to have disturbed the species distribution. However, here, the dams also appear to have positive effects. Some dam reservoirs supported the highest levels of species diversity, and as low as five dam sites contained over 95% of all species found. The dam reservoirs may therefore represent preferred sites for conservation, and the proper management of such reservoirs may be critical to balancing human needs with sustainable conservation of fish biodiversity. Copyright © 2014 John Wiley & Sons, Ltd.

The Asian catfish, Clarias batrachus (Linnaeus, 1758), is a highly valued species endemic to India that is currently in drastic decline in most of its natural habitat. The present study was undertaken to document the genetic structure of populations of this species using mitochondrial DNA markers, specifically from the cytochrome B and D-loop regions. Specimens from eight wild populations were collected and analyzed from different regions in India. The genetic variation within and among populations was evaluated using a range of descriptive statistics. The analysis described here provides a broad and consistent view of population structure and demographic history of populations of C. batrachus. Although there was some genetic structuring consistent with regional differences, all eight populations examined here showed relatively low levels of genetic variation in terms of both haplotype and nucleotide diversities in the different analyses used. However, a number of private haplotypes were discovered, and this may provide valuable information for future selective breeding program and conservation management. The results may aid in the design and implementation of strategies for the future management of this endangered catfish C. batrachus in India.