In this study, the effects of expansion control devices (ECD) used in the production of extruded fish feed pellets were investigated. Five types of experimental sea bass feed with different pellets diameter (3, 4, 5, 6 and 9 mm for S3, S4, S5, S6 and S9, respectively) based on commercial formulations (lower total vegetable ingredients but higher starch and protein amount in S3 feed) were produced without or with the usage of ECD during extrusion process. The pellets quality was compared based on: pellets diameter size, pellet hardness, pellet durability, sink rate, after-extruder density, after-cooler density, moisture, loss quantity measurements and physical appearance. The obtained results showed that the pellets produced with ECD had lower diameters except for S3 feeds. The sink rate, and after-extruder and after -cooler densities were higher, and loss quantity was reduced in pellets produced with ECD regardless pellets size. There were less dusty and cracked pellets in feeds produced with ECD. It can be concluded that the ECD could be successfully used in the production of extruded fish pellets contributing to lower production costs.