Fermentation of waste fish treated with Aspergillus oryzae, Aspergillus sojae K, and Saccharomyces cerevisiae IFO 2114 were studied independently and combined. Three microorganisms decreased the POV, MDA, and COY of fish meal at different rates. The optimum conditions for fermentation with the combination of three microorganisms was found at 30°C for 20-hr fermentation. Almost no difference was observed in the chemical composition or amino acid spectra of the protein hydrolysates of the fermented and nonfermented fish meal. On the quantity of water-soluble amino acids, the highest increase was in glutamate among others, but histidine was decreased by the combination of the three microorganisms. With A. oryzae, the highest increase was in phenylalanine and with A. sojae K in threonine. A great change was observed in some fatty acids content. Myristic acid (14:0) was decreased while the highest increase occurred in the linoleic acid (18: 2) content by fermentation with the combination of three microorganisms. The same phenomenum was observed with A. oryzae and A. sojae K. S. cerevisiae has a weaker effect than A. oryzae and A. sojae K in fermentation of waste fish.