Evaluation of Lignan as a Natural Hormonal Diluent for Enhancing Reproductive Performance of African Catfish, Clarias Gariepinus

Abstract

This study evaluated the effectiveness of lignan extracted from watermelon (Citrullus lanatus) seeds as a hormonal diluent during the artificial propagation of C. gariepinus. A completely randomised design consisting of five treatments was employed: 0% (control), 25%, 50%, 75%, and 100% lignan inclusion levels, each replicated three times. Reproductive performance indices, hormone residue levels, and water quality parameters were assessed. Results showed that lignan significantly influenced reproductive performance (P<0.05). The highest fertilisation rate (92.78%), hatchability (66.42%), and larval survival (52.53%) were obtained at 25% lignan inclusion, compared with 78.52%, 43.57%, and 37.72%, respectively, in the control group. Fecundity and relative fecundity were highest at 75% inclusion, while complete reproductive inhibition was observed at 100% lignan concentration. Hormone residue analysis at 24 and 48 hours revealed no significant differences (P>0.05) among treatments, indicating that lignan did not interfere with hormone metabolism or clearance. Water quality parameters remained within acceptable ranges and were not significantly affected by lignan inclusion. Third-order polynomial regression analysis identified approximately 35% lignan inclusion as the optimum concentration for hatchability enhancement, with a strong model fit (R² = 0.9596). The study demonstrates that lignan possesses reproductive-enhancing properties and can effectively function as a hormonal diluent during artificial propagation of C. gariepinus. Therefore, lignan represents a safe, environmentally friendly, and cost-effective alternative for improving hatchery performance and promoting sustainable aquaculture production.