To understand the regulatory mechanism of Vg induced vitellogenin synthesis the vg gene expression in Indian male walking catfish, Clarias batrachus was investigated. Semipurified conspecific Vg containing Vg1 and Vg2 in a ratio of 2.7:1.0 was administered into male catfish and vg cDNA (1.1kb) was amplified from total RNA in liver by reverse transcriptase polymerase chain reaction (RT-PCR) using primers designed from published sequence of Clarias macrocephalus. The nucleotide and deduced amino acid sequence of the cDNA shared maximum similarities (98–100%) with the corresponding sequences of known E2-induced Vg of C. batrachus and C. macrocephalus in the database. A 0.178kb cDNA fragment nested within the 1.1kb DNA was then amplified by real time PCR to evaluate the role of Vg on relative expression of vg gene. The result revealed a significant upregulation (1.79 fold) of vg mRNA at 6h reaching maximum level (9.78 fold) at 24h post Vg injection as compared to the saline control. Similarly, E2-treatment also showed maximum mRNA expression (7.73 fold) at 24h post injection. The findings suggest that like E2, Vg itself can induce vg gene expression resulting in a significant increase in plasma Vg levels (9.11±0.73mg/ml for Vg1 and 3.02±0.28mg/ml for Vg 2) in male catfish where E2 is lacking. The work provides further opportunity to study the regulatory mechanism of vg gene expression by Vg.