Comparison of responses to rapid changes in salinity between Hippocampus kuda and Oryzias melastigma

In order to explore the similarities and differences of responses between Hippocampus kuda and Oryzias melastigma, this study analyzed and compared them from the aspects of growth, behavior, physiology, and gene expression. The results showed that H. kuda had a greater impact on its feeding behavior compared to O. melastigma at the same rates. And the continuous responses of enzymes indicated there was a more persistent stress in H. kuda, with stress-related genes like sod1 showing a slower response. Additionally, genes related to sugar and lipid metabolism were significantly different in H. kuda compared to O. melastigma. H. kuda exhibited sensitivity to nearly all treatments, while O. melastigma only responded to treatments of direct input. Furthermore, the responses of immune-related genes in H. kuda were also slower than those in O. melastigma. In summary, the osmotic pressure regulation ability of O. melastigma was more efficient than that of H. kuda in dealing with the stress caused by rapid changes in salinity.