-.The diploid chromosome number (2n) and the chromosomal morphologies of the backcnxs progenies of Catia catia (Ham.) and Labeo rohita (Ham.) viz.-B^R and BCf^ developed in Central Agricultural Research Institute, Port Blair, South Andaman, India are reported for the first time through this study The B^R backcross generations includes carps developed by hybridization of S, backcross female and rohu male. The B, backcross individuals were developed by taking F, hybrid females from cross of catia female and rohu male hybridized with parental catia male. Similarly, the BCf^ backcross was developed by inter se breeding ofB^ backcross progenies. The conventional Giemsa-Flame drying technique of karyotyping provided first hand information regarding the cytogenetic character of the above two generations of backcross progenies. It was found that, the diploidy in both generations was 50, with variation in chromosomal morphometry i.e.- 2n=50: 14M +10SM+ 10 ST + 16 T/A in B^R and 2n= 50: 8M +12 SM + 22 ST + 8 T/A. in BCf