Karyotype studies in thirteen species of fishes

The karyotypes of thirteen species of fishes belonging to nine families, studied in spermatogonial cells and in primary and secondary spermatocytes are reported. All these fishes were collected from the river Jumna near Delhi (India). The diploid number of chromosomes of these species ranges between 86 (Wallago attu) and 40 (Ompak bimaculatus). The karyotypes of seven species are characterized by exclusively possessing acrocentric chromosomes, while the remaining six species have varying numbers of metacentric chromosomes in addition to acrocentric chromosomes. Species belonging to the same family, and even the same genus, have been found to differ in chromosome number and morphology.On the basis of the data available, the author has endeavoured to discuss the relationship between cytologically known fish species and the various complications involved in their classification. The validity of the nombre fondamental hypothesis of Matthey in fish karyotypes has also been discussed.