Genetic variability and ancient origin of the Japanese ornamental carp (koi) using the nucleotide sequences of mitochondrial DNA control region

• Published in: Aquatic Animals Vol. 2023; p. AA2023-18
• Main Author: Higuchi, Masahito
• Format: Journal Article
• Language: Japanese
• Published: Aquos Institute 23.08.2023
• Subjects: Actinopterygii; Cyprinidae; Cyprinus carpio; genetic variation; Nishikigoi; ornamental fish
• ISSN: 2434-8643
• DOI: 10.34394/aquaticanimals.2023.0_AA2023-18

The Japanese ornamental carp (koi) has a wide range of variation in external morphological features, including coloration and imprints, and is divided into numerous strains. Nucleotide sequence variation in the mitochondrial DNA (mtDNA) control region was analysed to discuss the origin of the koi. Analysis of eight Japanese koi strains yielded 926 or 925 base pairs of sequences from the entire mtDNA control region. Nucleotide base substitutions were observed at 25 sites (the rate of substitution site: 2.7 %) and 3 haplotypes were detected in the control region of the koi. Comparison of these haplotypes with sequences from carp in the DNA database showed that the most frequent haplotypes detected in the 6 strains of the koi in this study were also found in the Chinese edible colour carp (Oujiang colour carp) and were highly genetically related to haplotypes from Taiwan and Chinese carps. The remaining two haplotypes were observed from the Asagi and Platinum ogon strains of the koi. These haplotypes were genetically differentiated from the most frequent haplotype in the koi and were very closely genetically related to the haplotypes of the Japanese native common carp. These findings suggest that the Koi have several maternal lineages of carp, including a lineage genetically close to the Japanese native common carp, and the origin of the currently cultured koi was inferred to be polyphyletic.