Figla (factor in the germ line, alpha), encoding a germ cell-specific transcription factor, is a central regulator of oocyte-specific genes. In order to explore the potential role of Figla in fish gonadal differentiation, tilapia Figla gene was successfully targeted by TALENs (transcription activator-like effector nucleases) in XX individual and confirmed by genomic PCR and subsequent enzyme cleavage and sequencing. Consequently, the morphological and molecular changes in XX gonads were observed by H.E, IHC. Meanwhile, the alterations of E2 and 11-KT were also determined. From screening of different mutant genotypes with bases deletions (4, 8, 20, etc.), it was revealed that the efficiency of Figla gene targeting by TALEN was about 56.76%. Furthermore, deficiency of Figla gene in XX fish led to development of abnormal ovaries with severe degeneration or complete loss of oocytes and ectopic proliferations of somatic cells. Amazingly, IHC in Figla-deficient XX gonads revealed that male specific marker gene (Cyp11b2) for 11-KT production in leydig cells was expressed in the cells surrounding oocytes, however, Cyp19a1a was barely detectable which is strongly expressed in follicular cells of normal ovary. Notably, Figla deficiency led to dramatic decrease of E2 serum level along with augmentation in serum 11-KT level. Taken together, our data indicated that Figla might play an essential role in the ovarian differentiation and maintenance in tilapia fish.