Statement of significance:
The significance of this research is chiefly in determining the applicability of current theory of stress responses. Energy Homeostasis Theory has been developed and applied most often in the context of thermal tolerance, and studies examining osmotic stress have often been done in invertebrates which do not control body fluid osmolality. As such, it is unclear if the theoretical framework accurately describes the response of teleosts to hypersalinity, and whether biological indicators of crossing the critical threshold are useful. This study identifies key evidence for unique stress tolerance zones, and leverages powerful quantitative proteomics tools to describe the molecular phenotype in these zones. This information is valuable in understanding the impacts of salinity on teleost fish. It can be used to determine the level of salinity stress that individuals experience in the field.