In Pangasius fillet industries, soaking fillet with food additives such as sorbitol, sodium tripolyphosphate (STPP), and sodium chloride (NaCl) is a common practice to increase the quality of fillets. In this study, the fillets were soaked with different concentrations of sorbitol (1.32-4.68%), STPP (0.32-3.68%), and NaCl (1.32-4.68%) by using response surface methodology (RSM) with Central Composite Design with six replicates experimental design. The soaking solutions had a significant impact on weight gain, pH, and water activity (p