Abstract: The Karyotypes analysed were obtained from kidney cells of five marine fishes by means of injection of colchicine, hypotonic treatment and air-dry technique.The karyptype of Liza haematocheila on first pair of chromosomes. Similar karyotypes were described for 5 other species of the genus by Cataudella et all. (1974) and Choudhury(1979).Platycephalus indicus has a diploi chromosome number of 48, consisting of 2 pairs of metacentric, 3 pairs of submetacentric, 1 pair of subtelocentric and 18 pairs of telocentric chromosomes.The karyotypes of two species in Order of Pleuronectiformes, Paralichthys olivaceus and Kareius bicoloratus, were analysed. They have the same diploid chromosome number of 48, and similar karyotypes (48T). The secondary constrictions were observed on the fist pair of chromosomes in the two species. The diploid number of P. olivaceus from Yantai, China (2n=48)is different from that of the same species from Yamaguchi, Japan (2n=46), This may be one of the polymorphism in chromosomes.The diploid number of Fugu pseudommus is 44, and the karyotype consists of 12 metacentric, 8 submetacentric and 24 telocentric chromosomes.The cytogenetic causes of speciation in fishes were also discussed in the paper.