Economics of small-scale urban aquaponics in Brazil: a case study on Astyanax lacustris and Lactuca sativa

The objective was to examine the financial feasibility of a small-scale aquaponics system for producing tetra fish (Astyanax lacustris) as ornamental fish or live bait, alongside lettuce (Lactuca sativa) for human consumption. The initial investment required for implementing the project was US$ 40,118.06. The internal rate of return (IRR) varied from 13.2% for the minimum prices (US$ 0.15 and US$ 0.34 for tetra fish and lettuce, respectively) to 41.5% in the optimal scenario, with prices of US$ 0.14 for tetra fish and US$ 0.44 for lettuce. In the live-bait market, only at the minimum selling prices (US$ 0.15 for tetra fish and US$ 0.34 and US$ 0.39 for lettuce), the IRR fell below the minimum attractive rate of return set at 12%. Under the proposed conditions and scenarios, the evaluated aquaponic system presents a moderate risk in terms of economic viability.