INDUCTION OF XX PSEUDO-MALES, AND LARGE-SCALE REPRODUCTION OF ALL-FEMALE POPULATION IN YELLOW CATFISH

The shortage of female has impeded the development of aquaculture industry of yellow catfish (Tachysurus fulvidraco) in China in recent years. Therefore, large-scale production system of all-female is urgently needed. To produce an all-female population in large-scale of yellow catfish, 12—65 days post-hatching larvae were treated with the combination of three male-promoting factors, 17 α-Methyltestosterone (MT, 5 mg/kg), Letrozole (LZ, 300 mg/kg), and high temperature (33.5℃). XX pseudo-males were mated with normal XX females and large-scale production of all-female population was conducted. Results showed that the combination of MT, LZ, and high temperature-induced masculinization of XX individuals, and the completely sex-reversed XX males displayed a similar percentage of motile sperm with XY males. Histological observation found that there are a large number of spermatids in the testis of XX males, indicating normal reproductive ability. Subsequently, we mate XX males and XX females, produced 570000 genotypic XX larvae, and successfully reared them to large fingerlings in a pond. The results indicated that 2.8% and 12.0% XX individuals reversed to XX males which is probably due to the high temperature during the critical time of sex differentiation in the rearing pond. The ovary developed very well for the rest of XX females and can be used as female parents in the coming spawning season. The current work successfully conducted large-scale production of the all-female population in yellow catfish, and the results will provide an important foundation for the large-scale production system of the all-female population, and important safeguard for female selection in genetic breeding of new varieties.