Taxonomy of Finfish (1+2)

6.1.5.2 Staining of Chromosomes

The slides are stained in 4-5% Giemsa solution for the visualization of chromosomes. The karyotypic analysis in fishes is inherently difficult due to the presence of a large number of small-sized chromosomes. In many fishes the karyotypes are symmetrical, that is, the chromosomes are not much different in size and morphology. For example, the karyotypes in two species of tilapia consist of 22 pairs of chromosomes. Out of these, 20 pairs are very much similar in size and morphology and the remaining two pairs only look different. Thus it is difficult to discriminate these related species having identical chromosomes unambiguously. The development of chromosome banding techniques is a further advancement in the methodology that rendered the analysis of the chromosome morphology and structure with enhanced ability.