The population of cities in developing countries, especially Sub-Saharan Africa, is rapidly increasing . As cities grow, so does the demand for fish protein, means of livelihood and threat of climate change. While flow-through aquaculture can provide fresh, healthy and nutritious fish protein, it is plagued by extensive land requirement as well as effluent discharge. Alternatively, micro and small-scale Recirculating Aquaculture System (RAS) can improve food and nutritional security (FNS), livelihoods as well as reduce environmental degradation in urban areas. The question however remains - what are the key techno-economics issues , surrounding small-scale RAS in urban farming? This study reviews the RAS prototype of the Sustainable Aquaponics for Nutritional and Food Security in Urban Sub-Saharan Africa (SANFU) II project. The analysis is based on a simple mass balance, stock density, and cash-flow analysis. The results suggest that a concentration of solids out from the filtration of 0.015 kg/l in high fish stock density with limited space i.e. approx. 138 African Catfish - Clarias Garipinus in 600-liter tank can be achieved . An average monthly fixed and variable costs as well as revenues of ?16,700 (US$29) and ?32,535 (US$56) , respecteively, is attainable under certain conditions . Government policies on urban farming should promote RAS for FNS, environmental justice , and food system resilience.