Abstract.Ten strains ofVibrio anguillarumproduced three different types of iron‐binding compounds when cultured under different conditions. These were (1) a common phenolate siderophore produced by all strains. (2) a hydroxamate siderophore produced by three strains and (3) a second phenolate siderophore, tentatively identified as anguibactin, produced byV. anguillarumstrain 775 and two other strains, all of which contained a plasmid of 45–50 Md. The relative affinities of these siderophores, determined by competition for55Fe was: anguibactin