Mitochondrial cytochrome C Oxidase I (COI) sequence variation among the clariid fishes of India (Clarias magur, C. dussumieri and C. gariepinus) and their relationship with other representative clariids was studied in this work. Three species were sampled and together with 23 COI sequences from GenBank were used to reconstruct phylogenetic relationships in the family Clariidae. The study revealed two clades: one consisting of the African species with C. dussumieri, and the other of Asian species suggesting the prevalence of intra-continental diversification of catfishes. This study further revealed that the genus Clarias is monophyletic. For the COI gene, the interspecies genetic divergence ranged from 0.056 to 0.182. The mean genetic difference between C. dussumieri and other selected African species in this study is 12.1%. It was also observed that the morphological similarity of C. dussumieri and C. magur was not replicated in the genetic level. Clarias dussumieri was more close to African catfish C. gariepinus thus indicating the utility of COI phylogeny to identify the well-known African-Asian relationships within catfishes. The results also showed that C. magur and C. batrachus are genetically distinct from each other.

No abstract

The comparative assessment of genetic diversity using allozymes, random amplified polymorphic DNA (RAPD), and microsatellite markers was conducted in endemic and endangered yellow catfish (Horabagrus brachysoma) sampled from three locations in Western Ghats river systems of India. Among the three markers, microsatellites show more polymorphism, having 100% polymorphic loci, whereas allozymes show the least (56%). In RAPD, 60.5% of fragments were polymorphic. Observed heterozygosity and F(ST) values were very high in microsatellites, compared with the other markers. Microsatellite and RAPD markers reported a higher degree of genetic differentiation than allozymes among the populations depicted by pairwise F(ST)/G(ST), AMOVA, Nei's genetic distance, and UPGMA dendrogram. The three classes of markers demonstrated striking genetic differentiation between pairs of H. brachysoma populations. The data emphasize the need for fishery management, conservation, and rehabilitation of this species.

Summary To study the reproductive biology of Horabagrus brachysoma (Günther, 1864), monthly samples were collected from the riverine stretches of Lake Vembanad during 2001–2002. The sexes can be distinguished only during the breeding season; male to female ratio in the exploited catch was 1 : 1.97. The mean LT at first maturity (L50) was 18.5 cm in females and 17.5 cm in males. Absolute fecundity varied between 1100 and 124 000, with a mean of 20 472. The ovary showed group synchronous development and the oocyte diameter varied between 0.13 and 1.63 mm. The relatively high fecundity and hardy nature of H. brachysoma may favour the expansion of this indigenous catfish throughout the culture systems.

No abstract