This comprehensive review explores aquaponics as an environmentally friendly solution aligned with SDGs and food sovereignty, assessing various aspects from system design to automation, and weighing social, economic, and environmental benefits through literature and case studies. However, challenges persist in obtaining organic certification and legislative recognition, hindering its growth. Achieving remarkable water use efficiency, up to 90%, relies on adaptable fish species like Nile tilapia and carp. Nutrient-rich fish feeds notably benefit low-nutrient-demanding greens. Ensuring water quality and efficient nitrification are pivotal, supported by IoT systems. Despite its efficiency, integrating Industry 4.0 involves complexity and cost barriers, necessitating ongoing innovation. Economies of scale and supportive horticultural policies can bolster its viability. Aquaponics, known for its efficiency in enhancing crop yields while minimizing water use and waste, is expanding globally, especially in water-scarce regions. Aquaponics, pioneered by the University of the Virgin Islands, is expanding in Europe, notably in Spain, Denmark, Italy, and Germany. Asia and Africa also recognize its potential for sustainable food production, especially in water-limited areas. While it offers fresh produce and cost savings, challenges arise in scaling up, managing water quality, and meeting energy demands, particularly for indoor systems. Egypt’s interest in desert and coastal regions highlights aquaponics’ eco-friendly food production potential. Despite the associated high costs, there is a quest for practical and affordable designs for everyday integration. Research in arid regions and industry advancements are crucial for aquaponics’ global food production potential. Deeper exploration of intelligent systems and automation, particularly in large-scale setups, is essential, highlighting the industry’s promise. Practical application, driven by ongoing research and local adaptations, is a key to fully harnessing aquaponics for sustainable food production worldwide.

Aquaponics, the water-reusing production of fish and crops, is taken as an example to investigate the consequences of upscaling a nature-based solution in a circular city. We developed an upscaled-aquaponic scenario for the German metropolis of Berlin, analysed the impacts, and studied the system dynamics. To meet the annual fish, tomato, and lettuce demand of Berlin’s 3.77 million residents would require approximately 370 aquaponic facilities covering a total area of 224 hectares and the use of different combinations of fish and crops: catfish/tomato (56%), catfish/lettuce (13%), and tilapia/tomato (31%). As a predominant effect, in terms of water, aquaponic production would save about 2.0 million m³ of water compared to the baseline. On the supply-side, we identified significant causal link chains concerning the Food-Water-Energy nexus at the aquaponic facility level as well as causal relations of a production relocation to Berlin. On the demand-side, a ‘freshwater pescatarian diet’ is discussed. The new and comprehensive findings at different system levels require further investigations on this topic. Upscaled aquaponics can produce a relevant contribution to Berlin’s sustainability and to implement it, research is needed to find suitable sites for local aquaponics in Berlin, possibly inside buildings, on urban roofscape, or in peri-urban areas.

An indoor aquaponic system (i.e., the integration of fish culture with hydroponic plant production in a recirculating setup) was operated for maximizing water reuse and year-round intensive food production (Nile tilapia, Oreochromis niloticus, and leaf lettuce) at different fish feed to plants ratios. The system consisted of a fish culture component, solid removal component, and hydroponic component comprising six long channels with floating styrofoam rafts for holding plants. Fish culture effluents flowed by gravity from the fish culture component to the solid removal component and then to the hydroponic component. Effluents were collected in a sump from which a 1-horsepower in-line pump recirculated the water back to the fish culture tanks at a rate of about 250 L/min. The hydroponic component performed as biofilter and effectively managed the water quality. Fish production was staggered to harvest one of the four fish tanks at regular intervals when fish attained a minimum weight of 250 g. Out of the total eight harvests in 13 mo, net fish production per harvest averaged 33.5 kg/m³ of water with an overall water consumption of 320 L/kg of fish produced along with the production of leaf lettuce at 42 heads/m² of hydroponic surface area. Only 1.4% of the total system water was added daily to compensate the evaporation and transpiration losses. A ratio of 56 g fish feed/m² of hydroponic surface effectively controlled nutrient buildup in the effluents. However, plant density could be decreased from 42 to 25-30 plants/m² to produce a better quality lettuce.

The Maltese Islands food-water-energy nexus faces substantial challenges. These include increasing levels of land fragmentation and abandonment, an aging farming population and decreasing returns possible for remaining, often part-time, farmers. Demand for high quality, locally produced vegetables and seafood from natives, tourists and migrants continues to increase while production shrinks in the context of a rich traditional food culture. The country’s aquaculture sector also faces serious obstacles with exports facing tough competition and the tuna fattening industry dwindling because of reduced quotas. Water resources are also very scarce. Malta has no lakes or rivers and ground water is becoming increasingly brackish because of over-extraction, In terms of water resources per inhabitant, Malta is the most water stressed country in Europe and one of the ten most water-short countries in the world. Domestic supply of water is highly dependent on desalinization – an energy intensive process. Moreover, 90% of groundwater is of poor status and unfit for drinking because of nitrate pollution. This paper uses Malta as a case study to scope the potential of aquaponics to meet the complex demands of an economy with a high standard of living but extreme water-scarcity. Aquaponics – a closed cycle, soil-less method of cultivating crops that is highly water efficient and can reuse the limited effluents from intensive fish culture as a nutrient source, is assessed.