Goldfish (Carassius auratus auratus) are the most important ornamental fish and have closely genetic relationship with Carassius auratus.Some goldfish have obvious and beautiful oranda wen.However,how the oranda wen forms and grows is remained unknown.In this study,suppression subtractive hybridization (SSH) strategy was employed to construct a cDNA library that represented genes related to the wen.Wen tissue of 1-year oranda goldfish was treated as the tester and epithelial tissue on the head of 40-days oranda fry was treated as the driver.The housekeeping gene α-tubilin was used to detect the efficiency of the library and the α-tubilin mRNA expression decreased by up to 210-fold in the subtracted libraries compared with the un-subtracted samples,indicating a high subtractive efficiency.The result of nested PCR with adapter specific primers showed that the length of the inserts ranged from 100 bp to 2 000 bp.A total of 93 effective sequence with high otherness were identified by dot-blot screen and sequencing.ESTs in the library were compared,classified and annotated to common data base by bioinformatics analysis,and a set of special genes such as connective related genes and tumor-related genes,which could be involved in wen formation process of oranda goldfish,were identified,indicating that the cDNA library was constructed successfully.