The number of cytogenetic studies of fresh water fishes was increased in the recent years. Fish groups, such as Family: Characidae, comprises many of fishes which have economic importance. In the present study, the metaphase chromosomes and their karyotypes have been studied in three species of that family by using cytogenetic analysis. Fish species were Gymnocorymbus ternetzi, Moenkhausia sanctaefilomenae and Metynnis argenteus. All samples were collected from ornamental fish farms in Egypt. The diploid chromosome number and fundamental numbers of the three species under study were 2n = 50 and FN = 80, 2n = 50 and FN = 100 and 2n = 62 and FN = 122, respectively.