International Journal of Aquaculture, 2025, Vol.15, No.3, 99-115 http://www.aquapublisher.com/index.php/ija 112 Figure 2 (A) Collection site and natural habitat of Channa shingon in Kachin State, Myanmar; (B) lateral view and coloration of a live specimen in an aquarium; and vouchered specimen views showing; (C) lateral with pectoral fin pattern; (D) dorsal; and (E) ventral with lower side of head and thorax perspectives of C. shingon(Adopted from Hsu Htoo et al., 2025) In cold lake environments, snakeheads represented by the northern lineage of the black snakehead show strong cold resistance. They can still survive when the water temperature is close to freezing in winter, while the spotted snakehead enters a paralyzed state when it is below 10 ℃. This difference is likely to be derived from long-term natural selection, which has accumulated mutations in the black snakehead that ensure that cells can still produce energy at low mitochondrial temperatures. For example, the fatty acid composition of the mitochondrial membrane of the muscle of the black snakehead may have changed (partially unsaturated), reducing the membrane phase transition point; some mitochondrial enzymes such as ATP synthase may have improved the catalytic efficiency at low temperatures. These changes are inseparable from the support of genomic variation, among which mutations related to the mitochondrial genome should play a certain role. Ou et al. (2021) found through whole genome analysis that Channa argus and Channa maculata have different gene expression responses to low temperatures: Channa argus brain and liver rapidly activated a large number of differentially expressed genes at low temperatures. This suggests that Channa argus is genetically equipped with a mechanism to respond quickly to low temperatures. 7 Concluding Remarks Mitochondrial genome variation plays an important role in analyzing the phylogenetic relationships of the genus Snakehead. On the one hand, the whole mitochondrial genome sequence provides rich information for constructing a high-resolution phylogenetic tree, which clarifies the complex lineage relationships within the genus Snakehead. Many branch arrangement problems that were difficult to solve based on limited gene fragments in the past have been answered with the help of whole genome data, such as identifying new sister species pairs and clarifying the affiliation of major lineage groups. The systematic relationships revealed by mitochondrial variation are consistent with geographical distribution and morphological characteristics, which
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