Karyological features of some fish species except for family Cyprinidae from the Tigris river

Chromosome number and karyotype of Liza abu (Mugilidae); Mystus halepensis (Bagridae) and Mastecembelus simack (Mastacembelidae) from the River Tigris were observed first time. The diploid chromosome number of Liza abu was to be 48. The karyotype of this species consisted of 1 pair of metacentric, 23 pairs of acrocentric chromosomes and the arm numbers(NF) to be found as 50. In Mystus halepensis chromosome number was found to be 32 and 6 pairs of metacentric-submetacentric, 9 pairs of subtelocentric-acrocentric chromosomes, 1 submetacentric and 1 acrocentric with the arm numbers 45. On the other hand, Mastecembelus simack has 48 chromosomes and the karyotype consisted of 8 pairs of metacentric-submetacentric, 16 pairs of subtelocentric-acrocentric chromosomes with the arm numbers 64. Two metasentric chromosomes and 50 arm number which observed in Liza abu are the recorded first time for the mugilid fish. Reduced diploid chromosomes number in Mystus halepensis as 32 is also found first time for bagrid fish. The results which are determined in this study were compared with species belonging to these families recorded before and discussed their variation in chromosome number and karyotype with those given literarures. Key word: Liza abu, Mystus halepensis, Mastecembelus simack, Karyotype, Chromosome, Tigris River.