Inhibition of the growth of fish spoilage bacteria in naturally contaminated fish muscle, and in some instances of pure cultures of such organisms cultivated on laboratory media, by penicillic acid, 4-methoxy-2:5 toluquinone, methyl formate, ethyl formate, ethylene oxide, propylene oxide, methyl ether, ethyl ether, chloroform, ethylene dichloride, ethyl chloride, 1:4 dioxane, Chloramine B, Chloramine T, a mixture of isomeric glycerol formais, sodium chlorite, sodium benzoate, sodium nitrite, and one patent fish preservative was investigated. The results are discussed and are summarized in detail.