Abstract: In an in silico search for gonand specific expressed genes, we have identified zRAP55 which is enriched in the ovary of zebrafish .zRAP55 encodes a protein of 382 amino acids with a highly conserved Lsm domain. zRAP55 protein shares more than 56% identities with that of other vertebrate species. RT-PCR results show that it is predominantly expressed in the ovary. In situ hybridization and immunohistochemistry studies reveal that zRAP55 is ubiquitously dispersed throughout the cytoplasm of stages Ⅰ and Ⅱ oocytes, whereas no expression is observed in stages Ⅲ and Ⅳ oocytes. As an RNA associated protein, zRAP55 might function in the control of protein translation at the early stages of oogenesis in zebrafish.