Updated project metadata. Feeding a modified fish diet has been suggested to improve insulin sensitivity in bottlenose dolphins; however insulin sensitivity was not directly measured. Since demonstrating an improvement in insulin sensitivity is technically difficult in dolphins, we postulated that directional changes in the hormone axis: fibroblast growth factor 21 (FGF21)/Adiponectin/Ceramide (Cer), could provide further support to this hypothesis. Proteomic analysis of the serum proteins revealed few changes in serum proteins over the study period. In conclusion, changing the types of fish fed to dolphins resulted in increases in the insulin sensitizing hormone adiponectin and serum sphingosines consistent with an insulin sensitizing phenotype.