This paper reports an in-depth approach that identifies ascorbyl-2-sulfate (AS) in gastric, blood, liver, and muscle tissues of Atlantic salmon (Salmo salar). To insure the identify of the AS, the study utilized the latest high-performance liquid chromatography (HPLC) technology plus electron ionization mass spectrometry (EIMS). Just before saltwater adaptation stage, juvenile Atlantic salmon were force-fed AS, ascorbic acid (AA), and a molecular-equivalent combination of the two. After tissue analyses for AA and AS were performed by HPLC separation, the HPLC peaks were identified by EIMS. The data collected in this study indicate that Atlantic salmon can absorb AS through the gastric tissue when forced-fed AA and AS as described. The data also indicate that AS is transported through the blood to the liver. There is evidence to indicate that AS is converted to AA in the livers of these salmon. In addition, the muscle tissue contained a large portion of AA and AS.