Economic Analysis and Development of the Nile Tilapia Cultivated in the Nursery Using Reject Brine as Water Support

Reverse osmosis desalination is a solution for water supply in rural communities in the semi-arid region. However, the disposal of waste generated in the process has been a challenge. Thus, a study was conducted to evaluate the economic viability and development of Nile tilapia ( Oreochromis niloticus ) cultivated in nurseries using water support, the rejected brine from the brackish water treatment plant. The study was conducted in the rural community of Serra Mossoró, Mossoró, RN, Brazil, benefited by the “Água Doce” program with a desalination plant. For this, two nurseries were built for fish farming and a tank to receive fish effluent. Each nursery was populated with 700 male Nile tilapia fingerlings. To determine fish growth, biometric analyses of head length, partial length, total length, height, width, and average weight were performed every 30 days after stocking. The economic analysis consisted of identifying the financial inflows and outflows. The results showed that all biometric parameters increased linearly with the time of cultivation, indicating that tilapia development and production using reject brine were satisfactory, making this waste feasible in fish farming. Economically, the project proved to be unfeasible in the short term, requiring a longer execution time of the generated cash flows to cover the initial investment. Despite this, the project generated positive social and environmental impacts. The raising of tilapia is a viable alternative for draining saline waste and ensuring food and nutritional security for family farming.