The Study of Chromosomal Structure in Mystus pelusius (Solander in Russell,1794) Fish

Abstract

The present study was done to identify the karyotype of Mystus pelusius fish , which is theonly representative of the family Bagridae in Iraq, they have been caught from Tigris river inAL-Kraat area of Baghdad city, the results show that the diploid chromosome number was2n=32 and the males chromosomal types included 2n=(6m+13sm+7st+6t)and fundamentalnumber FN=51, in females chromosomal types included 2n=(6m+12sm+8st+6t)withFN=50,also it observed that the first submetacentric pair was the largest within the biarmedchromosomes .The results revealed that the male heterogamety and the female homogamety ,accordingly it follows the sex determination system (XX / XY) , as the (X) chromosomerepresented by medium sized submetacentric (sm)chromosome and (Y)chromosome by smallsized subtelocentric (st) chromosome.