Chromosomal Characteristics of the Three-Spot Damselfish, Dascyllus trimaculatus (Perciformes, Pomacentridae) in Thailand

The present study aims to analyze concerned karyotyping and idiograming of the three-spot damselfish (Dascyllus trimaculatus) in Thailand. Chromosomes were prepared from kidney tissues of fish reared at Institute of Marine Science, Burapha University, Chonburi Province. The mitotic chromosomes were harvested by the colchicine-hypotonic-fixation-air drying method. Conventional and Ag-NOR staining techniques were applied to stain the chromosomes. The results showed that D. trimaculatus had 2n=48, and the fundamental number (NF) was 50 without heteromorphic sex chromosomes. The types of chromosomes are 2 large acrocentric, 36 large terocentric and 10 medium telocentric chromosomes. The Ag-NOR banding exhibited that a single pair of NORs was presented on the short arm region of the large acrocentric chromosome. Basic knowledge on cytogenetics of D. trimaculatus would be applied for support of further studies on breeding, conservation and chromosome evolution in this fish. The karyotype formula of D. trimaculatus is as follows: