Gene expression profile were compared between left and right side of metamorphosing Japanese flounder (Paralichthys olivaceus). A pair of cartilage, Supra Orbital Bar (SOB), are formed symmetrically at the dorsal to the eyes, then right one degenerates proceeding the right eye migration. Small tissues around the SOB were dissected from left and right side and the gene expression profile were analyzed by RNA-seq using Illumina HiSeq2000.