Chromosomal Analysis of Two Snakehead Fishes, Channa marulius (Hamilton, 1822) and C. marulioides (Bleeker, 1851) (Perciformes: Channidae) in Thailand

The snakeheads, freshwater perciform fish are the member of the family Channidae. The karyotype diversification was observed in this species. In this study, we investigate the karyotype and chromosomal characteristic of nucleolar organizing regions (NORs) in Channa marulius (Hamilton, 1822) and C. marulioides (Bleeker, 1851) from Thailand. The metaphase chromosomes were prepared from kidney cells of five male and five female fishes. Conventional and Ag-NOR staining techniques were applied to the chromosomes. The results revealed that: the diploid chromosome number (2n) of C. marulius was 44, fundamental number (NF) was 56, the karyotype formula should be deduced as 2n=L-4(m)+L-6(a)+L-10(t)+M-2(a)+M-22(t), the NORs are located at the telomeric position of the short arm of chromosome pairs 3 and 4; the 2n of C. marulioides was 38, NF was 68, the karyotype formula should be deduced as 2n=L-8(m)+L-2(a)+M-2(m)+M-18(a)+M-8(t), the NORs are located at the telomeric position of the short arm of chromosome pairs 10 and 11. The difference of 2n and NF in males and females fish was not observed. The number of Ag-NORs in metaphase cell varies between two and four among the cells in the same sample both in C. marulius and C. marulio ides.