Summary This is the first heteromorphic nucleolar organizer regions (NORs) and chromosome analysis of Rolland s demoiselle (Chrysiptera rollandi). Kidney cell samples were taken from five male and five female fish. Mitotic chromosome preparations were prepared directly from kidney cells. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that the diploid chromosome number of C. rollandi was 2n=46, and the fundamental number (NF) was 50 in both males and females. The types of chromosomes were 2 large submetacentric, 2 large telocentric, 2 medium acrocentric, 32 medium telocentric, and 8 small telocentric chromosomes. In addition, the short arm of acrocentric chromosome pair 2a and the long arm of telocentric chromosome pair 6a (non-homologous chromosome) showed clearly observable NORs heteromorphic (2a6a) in both sexes and chromosome size was not related to sex. The karyotype formula for C. rollandi was:2n (

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