The study presents a potential alternative to synthetic hormones, pending further environmental safety evaluation, for the production of all-male Poecilia reticulata using ZnO nanoparticles loaded with Asparagus racemosus (Shatavari) and Withania somnifera (Ashwagandha) extracts. Plant extracts were prepared, characterized, conjugated with ZnO nanoparticles, and incorporated into feed at various concentrations. Fish were fed the experimental diets for 30 days, using a completely randomized design with eight treatments, including positive and negative controls. The particle size of ZnO nanoparticle, Shatavari-loaded ZnO nanoparticle and Ashwagandha-loaded ZnO nanoparticle was 6.96 nm (PDI 0.278), 58.00 nm (PDI 0.34) and 52.55 nm (PDI 0.31) respectively. The entrapment efficiency was found to be 48.52% for Shatavari loaded ZnO nanoparticles and 46% for Ashwagandha loaded ZnO nanoparticles. The FT-IR analysis confirmed successful conjugation of the plant extracts with ZnO nanoparticles and the presence of active phytochemicals. The treatment groups showed significant improvements in growth parameters and condition factor compared to the control, with the ZnO nanoparticle treatments exhibiting the best performance. The highest male percentage of 88.87% was recorded in Ashwagandha-loaded ZnO nanoparticle at 0.075 mg kg−1 and 0.05 mg kg−1 of feed with the survival of 90% and 95% respectively. The highest percentage of indeterminate individuals of 12.69% was found in treatment containing Shatavari-loaded ZnO nanoparticle (0.15 mg kg−1), showing delayed sexually dimorphic characters. The treatment groups exhibited higher Gonopodial Index values compared to the control, indicating enhanced development of male traits. These findings suggest that nano-conjugated plant extracts enhanced masculinization, growth, and survival rates in the fish. Future research should address the fate of ZnO nanoparticles to characterize their ecotoxicological implications better.
Hamdani et al. (2026) studied this question.