Abstract: Feminization-1 (fem-1) gene was first discovered in Caenorhabditis elegans, and it plays an important role in nematode sex determination. The mutation in fem-1c could feminize the nematode sex differentiation. There are three conservative members of fem-1 family in vertebrate, namely fem-1a, fem-1b and fem-1c. We cloned the entire cDNA sequence of fem-1c from zebrafish ovary cDNA library using RACE-PCR. The full length of zebrafish fem-1c cDNA was 2701 bp, encoding a 618-amino acid protein. We used online bioinformatic software and predicted that the FEM-1C protein contained 9 ANK domains, 2 TPR domains and 2 low complexity regions. Zebrafish FEM-1C shared a highly conservative protein sequence with its homologues in other vertebrates. The sequence analysis also revealed that in vertebrates there was a conservative synteny between fem-1c and its neighborhood genes, especially the nearest 45 genes such as tmed7 and trim36. We conducted the expression analysis in different tissues of adult zebrafish using RT-PCR and found that fem-1c was exclusively expressed in the ovary. The expression analysis in the gonad of larvae at different development stages showed that the expression of fem-1c began on the 17th day post-fertilization. The in situ hybridization results showed that fem-1c was expressed in cytoplasm at stage I and Ⅱ of oocyte. This specific expression pattern suggested that fem-1c might play a role in zebrafish ovary development.