Chromosome preparations of five species of fish were made from the kidneyby the air-flame drying method.The results are as follows: Channa maculatus-2n=42(4m+2sm+30t),NF=48;C.asiatica-2n=46(2sm+10st+34t),NF=48;C.argus-2n=48(12st+30t),NF=48; Labeo rohita-2n=50 (6m+4sm+14st+26),NF=60; Cirrhinus moli-torella-2n=50(20m+26sm+2st+2t),NF=90.The diploid numbers and chromosomal morphology of three species in Chan-nidae have been compared.They have the same fundamental arm number (NF=48),but the different diploid number(2n=42,2n=46,2n=48).We suggest that,Robert-sonian fusion reduces their chromosome numbers from 2n=48 to 46 or 42 oc-curred during the course of evolution and speciation.From the evolutionary po-int of view,the karyotype of C.argus with its great number of acro centrics andhigher diploid number appears more primitive than that of C.maculatus and C.a-siatica.On the contrary,the karyotypes of Labeo rohita and Cirrhinus molitorella haveidentical chromosome numbres of 2n=50,but the fundamental arm number is dif-ferent (NF=60,NF=96),Changes in fundamental arm number between them im-ply that uneven pericentric inversion and translocation of the chromosomes tookplace during the karyotypic evolution.Cytogenetic events of this sort may haveplayed a significant role in the divergence and speciation.The karyotype of Ci-rrhinus molitorellr with its few acrocentrics and many metacentrics may be con-sidered as more advanced than that of Labeo rohita.
