Transcriptomic changes in the brain of Limanda yokohamae were investigated to understand the environmental condition of Masan Bay, Korea. Differentially expressed genes (DEGs) in the brain of the flat fish from Masan Bay were identified by comparing those from the reference site Gangneung using annealing control primers-based polymerase chain reaction. The results demonstrated that two different kinds of the cytoplasmic ribosomal proteins, 40 s ribosomal protein S27a and ribosomal protein L6, were identified by the BLAST searching followed by sequence analysis. These findings suggest that environmental status of Masan Bay could hinder protein synthesis that is required for maintaining brain functions and thus cause the dysfunction of fish physiology.