A new gene with WD domains is cloned and characterized according to its differential transcription and expression between previtellogenic oocytes (phase I oocytes) and fully-grown oocytes (phase V oocytes) from natural gynogenetic silver crucian carp (Carassius auratus gibelio)by using the combinative methods of suppressive subtraction hybridization, SMART cDNA synthelowed by an open reading frame of 990 bp, which has the typical vertebrate initiator codon of Antranslated region and an AATAAA polyadenylation signal. Because it has 92% homology to STRAP (serine-threonine kinase receptor-associated protein), a recently reported gene, we named it FSTRAP (fish STRAP). Virtual Northern blotting indicated that the FSTRAP was transcribed in fully-grown oocytes (phase V oocytes), but not in previtellogenic oocytes (phase I oocytes).RT-PCR analysis showed that FSTRAP was transcribed in brain, heart, kidney, muscle, ovary,spleen and testis, but not in liver. And its mRNA could be detected in the oocytes from phase II to phase V. Western blotting also showed that FSTRAP protein could be detected in brain, heart,kidney, muscle, ovary, spleen and testis except liver. Results of Western blotting on various oocytes were also similar to the RT-PCR data. FSTRAP protein was not expressed in the previtelIogenic oocytes. Its expression initiated from phase II oocytes after vitellogenesis, and was consistent with the mRNA transcription.