Summary Infections caused by antibiotic‐resistant luminescent Vibrio s can cause dramatic losses in aquaculture. In this study, the short‐chain fatty acid β‐hydroxybutyrate and its polymer poly‐β‐hydroxybutyrate were investigated as possible new biocontrol agents. β‐Hydroxybutyrate was shown to completely inhibit the growth of pathogenic Vibrio campbelli at 100 mM. Moreover, the addition of 100 mM of this fatty acid to the cul...