Antifertility Activity of Mangifera indica Leaves in Nile Tilapia Oreochromis niloticus (Linnaeus, 1758)

Background: Tilapia (Oreochromis niloticus) is currently the second most farmed and produced fish group globally, accounting for approximately 3.49 million tonnes (Mt), following carp (24 Mt), and preceding clariids (2.97 Mt) and salmonids (2.36 Mt). Its prominence in aquaculture is attributed to a combination of favourable traits, including rapid growth rates, high tolerance to suboptimal water quality, efficient feed conversion, strong resistance to common diseases, widespread consumer acceptance, and its ability to spawn readily under culture conditions Aims: The aim of this study was to evaluate the potential of Mangifera indica (Mango) leaf methanolic extract as a natural reproductive inhibitor in Oreochromis niloticus (Nile tilapia). Methodology: The experiment was conducted from 21 February to 21 June 2024 at the Noun Chicken Fish Production Farm, located in Koutaba, Noun Sub-Division, West Region, Cameroon. A total of 450 mixed-sex juveniles of O. niloticus (mean initial weight: 13 ± 8.30 g) were randomly distributed into 15 happas (small-mesh net cages, 0.7 × 0.7 × 1 m) placed in a 6 m³ tarpaulin tank, at a density of 30 juveniles per happa, under natural temperature and photoperiod conditions. Five experimental diets were prepared: one control (untreated group) and four supplemented with M. indica leaf methanolic extract at doses of 0.08, 0.16, 0.24, and 0.32 g/kg feed. Fish were fed these diets for 45 days post-treatment, after which survival and zootechnical growth parameters were evaluated. Gonadal development was assessed through descriptive morphological examination at both 45 and 60 days post-treatment to determine the extract’s effects on reproductive performance. Results: Phytochemical screening of Mangifera indica leaves methanolic extract revealed the presence of alkaloids, tannins, saponins, and terpenes. The extract did not induce significant mortality across treated groups. However, growth performance analysis indicated that fish treated with 0.32 g/kg of M. indica leaf methanolic extract exhibited the most pronounced effects (p < 0.05), achieving an Average Weight Gain of 30.22 ± 1.41 g, Average Daily Gain of 0.43 ± 0.05 g/day, Specific Growth Rate of 1.78 ± 0.13 %/day, and an Average Condition Factor of 3.33 ± 0.17 %g/cm³.In contrast, reproductive parameters were markedly suppressed in treated groups. Males displayed significant reductions (p < 0.05) in gonadosomatic index (GSI), testicular weight, and length, while females exhibited decreases in GSI, ovary weight, fecundity, and mean egg diameter when compared with the control at both 45 and 60 days post-treatment. Morphological examination revealed pronounced gonadal atrophy in all treated groups, suggesting that the phytochemical constituents of M. indica—notably saponins, tannins, and alkaloids—may interfere with gonadal tissue development and steroidogenic pathways, leading to impaired reproductive function. Conclusion: The results of this study indicate that M. indica leaves can be used as a natural agent to control the reproduction of Nile tilapia and overcome the problem of early maturation. The results will help local producer networks to improve tilapia production.