Evaluation of Watermelon (Citrullus lanatus) Juice as a Natural Milt Diluent in the Artificial Propagation of African Catfish (Clarias gariepinus)

Aims: This study evaluated the qualitative parameters of African catfish (Clarias gariepinus) milt diluted with normal saline and watermelon (Citrullus lanatus) juice at different dilution ratios during induced breeding. Study Design: Completely randomised design (CRD) with six treatments and three replicates per treatment. Place and Duration of Study: The Teaching and Research Fish Farm and Limnology Laboratory, Department of Fisheries and Aquaculture Technology, Federal University of Technology, Akure, Ondo State, Nigeria, between October and December 2024. Methodology: Four apparently healthy broodstock of C. gariepinus (two males, 2.0 kg each; two females, 1.8 kg each) were selected based on maturity indices. Milt was collected from dissected males into dry vials and diluted at different ratios of saline and watermelon juice: 1:0:0 (T1, control), 1:10:0 (T2, reference), 1:7.5:2.5 (T3), 1:5:5 (T4), 1:2.5:7.5 (T5), and 1:0:10 (T6). Sperm quality (motility, motility duration, pH, and concentration), fertilisation, hatchability, egg adhesiveness, and larval survival were evaluated. Data were analysed using one-way ANOVA, and means were separated with Duncan’s multiple range test at a 5% significance level. Results: Significant differences (p < 0.05) were observed in sperm motility, motility duration, and pH across treatments, while sperm concentration showed no significant variation (p > 0.05). The highest motility percentages were obtained in T4 (56.64%) and T5 (56.94%), compared with the lowest in T1 (24.16%). Fertilisation success ranged from 85.62% in T5 to 91.76% in T4, with T4 also recording the best hatchability (75.89±1.57%) and survival outcomes (75.41±2.57%). Physiochemical parameters of water during the culture period (temperature, dissolved oxygen, and pH) remained within optimal limits for C. gariepinus breeding. Conclusion: Watermelon juice (Citrullus lanatus) demonstrated strong potential as a natural and cost-effective diluent for milt in artificial propagation of African catfish. The 1:5:5 dilution ratio (milt:saline:watermelon juice) proved most effective, producing optimal sperm motility, fertilisation, hatchability, and larval survival.