Evaluating the Adaptation of Tilapia Strains to Brackish Water Conditions for Sustainable Aquaculture in Sub-Saharan Africa

Abstract

The present study aimed to compare the adaptability of the Bouaké and Brazil strains of Oreochromis niloticus to brackish lagoon conditions in order to identify the strain best suited to intensive lagoon aquaculture in Côte d’Ivoire and to contribute to the diversification and optimisation of national and sub-Saharan African aquaculture production. A total of 3,600 fingerlings (initial mean weight: 5 g) were stocked equally in two 600 m² lagoon enclosures and reared for eight months (July 2024 to February 2025). Fish were fed a commercial diet, while water-quality variables and zootechnical indicators were monitored monthly. Salinity increased during the study from approximately 0.08 to 6.88‰, with similar mean values between the enclosures. The Brazil strain showed higher final body weight (603.92 ± 68.30 g vs. 429.38 ± 58.29 g), total length (28.74 ± 0.79 cm vs. 25.06 ± 1.64 cm), daily weight gain (2.50 ± 0.28 g day⁻¹ vs. 1.77 ± 0.24 g day⁻¹), and specific growth rate (1.99 ± 0.05% day⁻¹ vs. 1.85 ± 0.06% day⁻¹) than the Bouaké strain. It also had a lower feed conversion ratio (1.67 vs. 2.47). Conversely, survival was higher in the Bouaké strain (97.03 ± 4.17%) than in the Brazil strain (68.23 ± 10.89%), and the Bouaké strain had a higher condition factor. These findings describe contrasting performance profiles under the lagoon conditions tested: the Brazil strain achieved greater growth, whereas the Bouaké strain showed higher survival. However, because the study used only one enclosure per strain and water-quality conditions were not identical between enclosures, the observed differences cannot be attributed solely to strain effects. In addition, salinity increased during the rearing period. Replicated and randomised trials are therefore needed to confirm these results and support strain selection for intensive lagoon aquaculture in Côte d’Ivoire.