The biological diversity and aquaculture of clariid and pangasiid catfishes in South-East Asia : proceedings of the mid-term workshop of the 'Catfish Asia project'

Ten crosses between five #Clarias$ species of African (#C. gariepinus$) and Asian origin (#C. batrachus$, #C. meladerma$, #C. nieuhofii$ and #C. teijsmanni$) were evaluated on the basis of the fertilisation and hatching rates obtained. Zootechnical performances (growth, survival) of #C. batrachus$ and #C. gariepinus$ larvae were compared. Viable hybrids growth and survival were followed up until the age of 11 weeks. The genotype of the reciprocal crosses between #C. gariepinus$ and #C. meladerma$ was studied and the gonad development of two-years-old #C. meladerma$ x #C. gariepinus$ hybrids were examined (inter-specific crosses are always given with the female parent in the first position). No hybrid between #C. gariepinus$ and #C. batrachus$ could be obtained. #Clarias gariepinus$ x #C. nieuhofii$ and #C. gariepinus$ x #C. teijsmanni$ hybrids did not survive more than a few hours after hatching and larvae obtained from #C. gariepinus$ x #C. meladerma$ cross were non viable beyond a few days afer hatching. In the latter case, protein electrophoresis of progeny carried out at two loci diagnostic for #C. gariepinus$ and #C. meladerma$) (PGI and PGM) indicated that the larvae resulted from an haploid gynogenetic development. The crosses between female #C. meladerma$ and male #C. gariepinus$ or #C. nieuhoffi$ or #C. teijsmanni$ produced viable hybrids. #Clarias gariepinus$ and #C. batrachus$ zootechnical performances comparison during larval rearing indicated that the growth potential of these two species is equivalent until the age of 12 days, though #C. gariepinus$ is favoured by its larvae bigger initial size. The comparison of #C. gariepinus$ and #C. meladerma$ x #C. gariepinus$ growth and survival until the age of 11 weeks showed good performances in the hybrid compared to the Asian species but slightly lower than the ones observed in #C. gariepinus... (D'après résumé d'auteur)