Synergistic Effect of Salinity and 17β‐Estradiol on the Induced Feminization of Centropomus undecimalis : Histological, Hormonal, and Molecular Evaluation

The scarcity of functional females in wild Centropomus undecimalis populations limits broodstock development for aquaculture. This study evaluated feminization of this protandrous hermaphroditic teleost under different salinity conditions using 17β‐estradiol (E2), administered orally to juveniles and via intramuscular implants to adults. Two factorial experiments assessed E2 effects on histological, hormonal, molecular, and zootechnical parameters. Complete feminization was achieved in both juveniles and adults, as confirmed by histological analysis and upregulation of female sex and reproduction‐related genes ( foxl2a , cyp19a1a , zar1l , ddx5 , and H2A ), with the most pronounced responses under marine conditions. Hormonal assays indicated increased plasma vitellogenin (Vtg) and reduced 11‐ketotestosterone (11‐KT) in treated groups, reflecting suppression of male endocrine pathways. Zootechnical performance in adults was not significantly affected. However, juveniles reared in freshwater demonstrated superior feed conversion and protein efficiency compared to those in marine conditions, independent of hormone treatment, indicating that salinity influences growth efficiency. These results confirm that E2‐induced feminization is highly effective across salinities and life stages, with salinity modulating molecular and productive outcomes, offering practical recommendations for broodstock development and sustainable management of wild snook populations.