Evaluation of the Microbiological Quality of Water in Different Tilapia Rearing Structures in Côte d’Ivoire

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The intensification of tilapia aquaculture in Côte d’Ivoire increases the importance of monitoring the microbiological quality of rearing water. This study evaluated water used to rear Nile tilapia (Oreochromis niloticus) in three rearing structures: earthen ponds, concrete tanks and aquariums. Water samples were analyzed using culture-based methods for bacterial indicators, potentially pathogenic bacteria and microfungal groups. The detected microorganisms included total coliforms, intestinal enterococci, Aeromonas spp., Aeromonas hydrophila, Salmonella spp., Escherichia coli, Staphylococcus aureus, Saprolegnia spp., Aspergillus spp., unidentified yeasts and unidentified moulds. Microbial loads varied among the rearing structures. Tank water showed the highest bacterial contamination, with Salmonella spp. reaching 14,000 ± 350 CFU/100 mL, and also recorded the highest total coliform, Staphylococcus aureus, unidentified yeast and unidentified mould loads. Pond water showed intermediate bacterial contamination and the highest Saprolegnia spp. load (200 ± 10 CFU/100 mL). Aquarium water showed the lowest detection of the investigated microorganisms. Total coliforms were detected at 500 ± 40 CFU/100 mL, whereas the other investigated bacterial and microfungal groups were recorded at 0 ± 0 CFU/100 mL. These findings indicate distinct microbial profiles among the three rearing structures. Regular sanitation, adequate water renewal and systematic microbiological monitoring are recommended to support fish health and strengthen biosafety in tilapia production systems.