Karyological study of Ctenopharyngodon idella ♀× Hypophtalmichthys nobilis ♂ F1 hybrids

In this study, the cytogenetic characteristics of F1 progeny produced by artificial crossing between female grass carp and male big head carp Ctenopharyngodon idella ♀× Hypophtalmichthys nobilis ♂ were investigated using tissue-squashing of head kidney and giemsa staining method. A total 75 methaphase plates obtained from 15 individual hybrid fish (average weight 18 g) were investigated and different chromosomal characteristics such as chromosome no, NF, short and long arm length, centromic index, arm ratio, total length of chromosomes and its variations were determined and karyogram and ideogram of chromosomes were created using suitable samples. The final results showed that, in comparison with parents, the hybrids were triploid with 3n=72 and NF=132. The karyotype showed that these hybrids had 27 metacentric (m), 33 submetacentric (sm) and 12 acrocentric (a) chromosomes. The karyological parameters of triploid hybrids showed that the centromic index, arm ratio, relative length and length variation range of chromosomes were 19.20-46.80, 1.13-5.60, 7.53-2.54 and 1.27 -3.83 μm respectively. The total length of chromosomes in haploid series and NF were 50.51 μm. Longest and shortest chromosomes of triploid hybrids were a series of acrocentric and submetacentric respectively.