The optimum boiling condition was determined for fish extracts by response surface model. Model equations were designed with effect of time (T) and the amount of added water (W) on the level of released free amino acid. Based on the high (>0.9) coefficient of determination and low (<0.01) level of significant, those model was approved to be significant. The added water amount of higher regression coefficient $ (eta_2)$, showed a greater influence on releasing free amino acids than boiling time. The optimum boiling times are 6 hours for crucian carp, 5 hours for bastard halibut, 7 hours for loach and 5 hours for jacopever. The ratio of added water to sample 1 (v/w) could be applied to all fish samples at $100pm2^{circ}C.$