The aim of this study was to determine the effects of different soy protein concentrate (0, 15, 30, and 45%), defatted soy flour (0, 10, 20, and 30%), and wheat flour (10, 20, and 30%) contents replacing fish meal on physiochemical properties of extruded aquatic feed by using a twin screw extruder. The moisture content, barrel temperature, die diameter, and screw speed were adjusted to 45%, 137oC, 4 mm, and 250 rpm, respectively. With the higher amount of soy protein concentrate replacing fish meal, the expansion ratio, swelling ratio, and water stability increased significantly while specific length and water holding capacity decreased significantly. With the increasing defatted soy flour content, expansion ratio increased significantly, but specific length, water holding capacity and water stability decreased significantly. With increase in the wheat flour content, the specific length significantly decreased while the water stability significantly increased. In conclusion, aquatic feed quality was optimized in this study and could be used in the future.

Abstract
 Introduction
 MATERIALS AND METHODS
 Results and Discussion
 Conclusion
 References

• Xuelian Ma(Department of Food Science and Technology, Food and Feed Extrusion Research Center, Kongju National University)
• The-Thiri Maung(Department of Food Science and Technology, Food and Feed Extrusion Research Center, Kongju National University)
• Tie Jin(Department of Food Science and Engineering, Yanbian University)
• Jin-Hyung Yoo(Korea Aquatic Life Institute Co.Ltd)
• Mi-Hwan Kim(Department of Food Science and Technology, Food and Feed Extrusion Research Center, Kongju National University)
• Gi-Hyung Ryu(Department of Food Science and Technology, Food and Feed Extrusion Research Center, Kongju National University) Corresponding author