Ten days post-hatch, juveniles received one of the four following infection treatments: (i) no injection – control (c), (ii) sham injection of autoclaved seawater (sw) with the equivalent salinity, i.e., 15 or 7 PSU, (iii) injection of Vibrio alginolyticus strain K01M1, which evolved for 90 days under laboratory condition at 15 PSU (v15) or (iv) Vibrio alginolyticus strain K01M1 that had evolved for 90 days under laboratory condition at 7 PSU (v7). One day after the injection, one juvenile was removed and used for the measurment of targeted gene expression. The size of this individual is listed in the dataset as well as the number of juvenile pipefish alive or dead (cummulative) for each treatment, replicate and timepoint of the survival experiment.