The efficient production of lactic acid, standardization of ingredients, protein hydrolysis, and the presence of an active starter were key factors for development of a controlled lactic acid fermentation of fish wastes and papaya. The maxima buffering capacities, proteases activities, protein and ash contents were considered for the selection of the suitable mixture of bones, fins, viscera, heads and dark meat. In addition, the overproduction of papaya is commonly presented in tropical countries, and herein, papaya surpluses were successfully employed as carbon source for Lactobacillus plantarum fermentation of tuna toward the production of added value protein hydrolysates.  The maximum lactic acid produced, acidification rate constant and maximum acid production rate were estimated by Gompertz model with experimental data of 5 d of 1.27 mmol of lactic acid/g, 0.142 1/h and 0.067 mmol LA/gh, respectively. The highest degree of hydrolysis of 87.71% was achieved at 120 h. The radical-scavenging activity of the protein hydrolysates was determined by electron paramagnetic resonance spectroscopy analyses based on the conversion of 2,2-diphenyl-1-picrylhydrazyl free-radical. In addition, the lowest concentration of tuna protein hydrolysates (5.75 µg protein/mg) that gave the half-maximal inhibitory concentration was determined at 72 h of fermentation.