| dc.description.abstract | The Siam catfish (Pangasianodon hypophthalmus) is one of leading commodity in freshwater fish farming, widely recognized by Indonesians for many years. From a systematic perspective, the Siam catfish (Pangasianodon hypophthalmus) is classified under the family Pangasiidae, order Siluriformes, and genus Pangasianodon .This study aims to compare the results of previous research that indicated differences in karyotype patterns, with a focus on the karyotype characteristics of the Siam catfish (Pangasianodon hypophthalmus) using IdeoKar 1.3 software. The research used descriptive method, in which colchicine was administered at a concentration of 0.007% for 8 hours, followed by treatment of the gills with a hypotonic KCl solution and Carnoy’s fixative. Chromosome preparations were made by using the solid tissue technique and stained with 5% Giemsa. Data were analyzed by IdeoKar version 1.3 and Adobe Photoshop CS3 to observe the number ,the shape and the size of the chromosomes. The results of the study also find that the chromosome of the Siamese catfish (Pangasianodon hypoptalmus) has 30 pairs of diploid chromosomes (2n=60) with 15 pairs of metacentric chromosomes and 15 pairs of telocentric chromosomes. The Siam catfish (Pangasianodon hypoptalmus) has the largest chromosome size at 9.97 µm, the highest r value at 0.96, a relative length percentage of 6.73%, a total form percentage (TF%) of %, an asymmetry index (Ask%) of 65.29, an average centromere index (Xcl) of 0.23, and a haploid chromosome complement length (HCL) of 143.67. The chromosome shape in the karyotype of the Siamese catfish (Pangasianodon hypopthalmus) shows a tendency to be asymmetric, meaning that the chromosomes have a striking difference in length between the short and long arms. This characteristic indicates that the karyotype of this species is more advanced in the context of chromosome evolution and differentiation. | en_US |
