Prevalence and co-infections of pathogenic bacteria in Nile tilapia broodstock farms: implications for aquaculture management in Togo.

This study aimed to evaluate the prevalence of E. coli, Pseudomonas spp., and Enterococcus spp. in Nile tilapia broodstock farms in Togo and their association with fish diseases. In total, 60 samples were collected from two tilapia broodstock farms, including 40 broodstock tilapia and 20 water samples. Each farm had concrete tanks supplied with water from two drills. Of the 40 fish samples, 20 were healthy, and the other 20 were diseased. Microbiological analysis of samples was conducted using standardized methods. The study revealed significant contamination in all collected water samples, detecting multiple bacterial populations. Bacterial infections were more prevalent in symptomatic fish, with 85% exhibiting co-infections (df = 1, χ2 = 7.03, p = 0.008). Contamination levels varied among sample types, with higher counts observed in wastewater (E. coli: 0-300 CFU/mL, Pseudomonas spp.: 3-300 CFU/mL, Enterococcus spp.: 0-55 × 102 CFU/mL) compared to drilling water (Pseudomonas spp.: 0-300 CFU/mL, E. coli: 3-400 CFU/mL, Enterococcus spp.: 0-14 × 102 CFU/mL), and intestinal samples (E. coli: 0-120 × 102 CFU/mL, Enterococcus spp.: 0-170 × 102 CFU/mL, Pseudomonas spp.: 0-60 × 102 CFU/mL) (df = 21, χ2 = 59.31, p < 0.000). Our findings emphasize the significant prevalence of pathogenic bacteria in Nile tilapia broodstock farms in Togo, highlighting the importance of water quality management and infection control strategies. Further studies are required to develop appropriate prevention strategies.

Optimization of feed for Nile tilapia (Oreochromis niloticus) using an Excel programming model in small-scale feed-mixing operations in Togo.

This study aims to develop an Excel programming model to formulate feed for Nile tilapia (Oreochromis niloticus), mainly for small- and medium-sized fish feed manufacturers. The model allows users to formulate the least costly balanced diet of Nile tilapia species, giving them the ability to choose a specific ingredient in the formulation according to the realities of the local environment: space-temporary availability of ingredients, prices and nutritional quality. Computer programming of a database of 25 locally available feed components was carried out using the Excel Solver Add-in and Excel IF mathematical functions to incorporate/delete specific ingredients in real time in accordance with user objectives. The theoretical characteristics of the least-cost balanced diets performed were within the margin of the nutrients requirement of the target fish size with protein levels of 35 per cent (fry diet: $1.07/kg), 32 per cent (fingerlings diet: $0.48/kg), 29 per cent (growth diet: $0.43/kg) and 27.12 per cent (final diet: $0.39/kg). The digestible energy of these diets was between 3016.5 ± 93.8 kcal. In addition, the model shows that an increase in soya meal prices by 75 per cent led the local feed industry to rely on imported fish meals, as the number included reached 52.28 per cent. However, the cost of the diet margin did not vary significantly. Nevertheless, it would be important to test the balanced diet developed with the model before production and scaling.