Abstract: The mtDNA D -loop region of 136 bluntnose blackbream Megalobrama amblycephala from the cultivated populations of Jixian, Ninghe and Taiyuan was amplified by Polymerase Chain Reaction （PCR） and digested by 14 restriction endonucleases, that is, being analyzed by restriction fragment length polymorphism （RFLP）. The results showed that the restriction sites were observed by 9 enzymes, with two of which, Xsp I and Mbo I , polymorphism could be observed and 2 haplotypes were scored. The populations of Jixian and Taiyuan belonged to one haplotype. The Ninhe population had 2 haplotypes. The haplotype diversity indices and nucleotide diversity indices within the Jixian and the Taiyuan populations were both 0, respectively, but within Ninhe population they were 0.0850 and 0. 001312. The nucleotide divergence and the Rogers＇distance between the Ninghe population and the Jixian （or P Taiyuan） population were 0.000015 and 0. 0435, respectively. Thex2test showed that there was no significant variance among three populations. As a result, the genetic diversity in the mtDNA D - loop region of bluntnose blackbream was quite low.
2007, Vol. 22 
