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TGF-β receptors play important roles in mediating TGF-β signals during gonadal development. To identify the functions of TGF-β receptors, including the type I receptor (activin receptor-like kinase 5, <i>ALK5</i>) and type II receptor (bone morphogenetic protein receptor 2, BMPR2), during the gonadal development of <i>S. prenanti</i>, the full-length cDNA sequences of <i>ALK5</i> and <i>BMPR2</i> were isolated and characterized. Their expression patterns in developing gonads and in the gonads of exogenous estradiol (E₂) -fed fish were analyzed. The cDNAs of <i>ALK5</i> and <i>BMPR2</i> were 1925 bp and 3704 bp in length and encoded 501 and 1070 amino acid residues, respectively. <i>ALK5</i> and <i>BMPR2</i> were mostly expressed in gonads, particularly in cortical alveoli stage ovaries and mid-spermatogenic stage testes; however, the overall level of <i>BMPR2</i> mRNA was higher than that of <i>ALK5</i> during gonadal development. Furthermore, immunohistochemical signals of ALK5 and BMPR2 were mostly detected at chromatin nucleolar oocytes and perinuclear oocytes in ovaries and at spermatocytes and spermatogonia in testes. Exogenous E₂ induces the gonadal expression of <i>ALK5</i> and <i>BMPR2</i>, and <i>BMPR2</i> is more responsive to E₂ than <i>ALK5</i>. These results suggest that ALK5 and BMPR2 might play a potentially vital role in both folliculogenesis and spermatogenesis in <i>S. prenanti</i>.