Abstract

• The present research was conducted to study chromosomal variations and karyogram of Cyprinus carpio and Labeo rohita from Mondaing Dam, Meiktila Township, Mandalay Region. The study period lasted from July 2022 to January 2023. For chromosome preparation, 0.5 ml of blood sample was extracted from the caudal vasculature of selected specimens and mixed with 0.5% colchicine 0.5 ml and 100% sodium chloride (hypotonic solution) 1 ml. Then, tested for different durations of 1 hour 30 minutes, 1 hour 45 minutes, 2 hours, 2 hours 15 minutes, 2 hours 30 minutes and 2 hours 45 minutes and stained with undiluted Giemsa for 15 minutes. Finally, the two slides of the treated cell suspensions were fixed in two or three drops of Carnoy’s fixative solution. The optimum metaphase spreads were observed at 2 hours and 15 minutes in C. carpio and 2 hours and 30 minutes and 2 hours and 45 minutes in L. rohita. The karyotype results of two fish species indicated that the diploid number of C. carpio was 2n = 100 with 28 metacentric (m), 38 submetacentric (sm), 12 acrocentric (a) and 22 telocentric (te) chromosomes with the number of fundamental arms was 166. The diploid number of L. rohita was 2n = 50 with 16 metacentric (m), 14 submetacentric (sm), 12 acrocentric (a) and 8 telocentric (te) chromosomes with the number of fundamental arms was 82.