using a routine method including intraperitoneal injection of PHA and colchicine, air-drying, and staining. In addition, we determined the erythrocyte nuclear DNA content of using flow cytometry, with chicken erythrocytes (2.50 pg) as a standard. The diploid chromosome number of was 2n=100, and the karyotype was 2n=. The secondary constriction, satellite chromosomes, and heterosomes were not observed. Silver staining revealed that most chromosomes featured a pair of Ag-NORs. The ranged from 1 to 2 in the interphase nucleus, but Ag-NOR combinations were not observed. We estimated the diploid cellular DNA content of , and is a member of the primitive fishes in the specific classification order.