were discovered in the main stem of the Irtysh Rive (the Crop 185) in May 2008. We defined them as high-dorsal silver crucian carp2.39) based on differences in their morphology (body length/body depth). The number of lateral line scales in the high and low-dorsal is 31 and 30, respectively. The number of scales above (or below) the lateral line is 7 (6), the number of scales above (or below) the lateral line in the caudal peduncle is 3 (2). High-dorsal exhibit a size advantage based on the significant difference in body depth and width, head depth and width, and caudal peduncle depth (<0.01) between high and low-dorsal silver crucian carp. A comparison of the mitochondrial control region sequences of the two types revealed that each has one haplotype, thus representing intraspecific variation with a low genetic diversity value (0.004). The two types and Fangzheng in the Heilongjiang River are monophylic, and share the same haplotype with Fangzheng . Accordingly, we speculate that the Irtysh silver crucian carps are derived from the Heilongjiang River basin. Our observations suggest the two types of , particularly the high-dorsal , have a growth advantage over other crucian carps. Given this, they offer greater potential as breeding stock. Our results provide a theoretical basis for better conservation and utilization of the unique varieties of Irtysh River silver crucian carp.