Fish protein hydrolysates were produced from Kilka (Clupeonella cultiventris), a major clupeonella species in the Caspian Sea. Fish protein hydrolysate was produced from the hydrolysis conditions (enzyme/protein substrate concentration %, temperature, and time) were optimized using response surface methodology. The optimum conditions to reach the highest degree of hydrolysis were: 39.64^°C, 21.02 min, and a protease (Promod) 1.36 %. Kilka protein hydrolysates had relatively high protein (75.36%).