Current applications of aquaponics
This final section briefly discusses some of the major applications of aquaponics seen around the world. This list is by no means exhaustive, but rather a small window into activities that are using the aquaponic concept. Appendix 6 includes further explanation as to where and in what contexts aquaponics is most applicable.
Domestic/small-scale aquaponics
Aquaponic units with a fish tank size of about 1 000 litres and growing space of about 3 m2 are considered small-scale, and are appropriate for domestic production for a family household (Figure 1.6). Units of this size have been trialled and tested with great success in many regions around the world. The main purpose of these units is food production for subsistence and domestic use, as many units can have various types of vegetables and herbs growing at once. In the past five years, aquaponic groups, societies and forums have developed considerably and served to disseminate advice and lessons learned on these small-scale units.
Semi-commercial and commercial aquaponics
Owing to the high initial start-up cost and limited comprehensive experience with this scale, commercial and/or semi-commercial aquaponic systems are few in number (Figure 1.7). Many commercial ventures have failed because the profits could not meet the demands of the initial investment plan. Most of those that do exist use monoculture practices, typically the production of lettuce or basil. Although many academic institutes in the United States of America, Europe and Asia have constructed large units, most have been for academic research rather than food production, and are not intended or designed to compete with other producers in the private sector. There are several successful farms throughout the world. One group of experts in Hawaii (United States of America) has created a fully-fledged commercial system.
They have also been able to obtain organic certification for their unit, enabling them to reap a higher financial return for their output. Another large-scale and commercially successful aquaponic operation is located in Newburgh, New York (United States of America), and reaps profits through multiple revenue streams from diverse fish and vegetable species and a successful marketing strategy to local restaurants, grocery, and health food and farmers markets.
Detailed business plans with thorough market research on the most lucrative plants and fish in local and regional markets are essential for any successful venture, as is experience with small-scale aquaponics, commercial aquaculture and commercial hydroponics.
Education
Small-scale aquaponic units are being championed in various educational institutes including, primary and secondary schools, colleges and universities, special and adult education centres, as well as community-based organizations (Figure 1.8). Aquaponics is being used as a vehicle to bridge the gap between the general population and sustainable agricultural techniques, including congruent sustainable activities such as rainwater harvesting, nutrient recycling and organic food production, which can be integrated within the lesson plans. Moreover, this integrated nature of aquaponics provides hands-on learning experience of wide-ranging topics such as anatomy and physiology, biology and botany, physics and chemistry, as well as ethics, cooking, and general sustainability studies.
Humanitarian relief and food security interventions
With the advent of highly efficient aquaponic systems, there has been an interest in discovering how the concept fares in developing countries. Examples of aquaponic initiatives can be seen in Barbados, Brazil, Botswana, Ethiopia, Ghana, Guatemala, Haiti, India, Jamaica, Malaysia, Mexico, Nigeria, Panama, the Philippines, Thailand and Zimbabwe (Figure 1.9). At first glance, there appears to be a considerable amount of aquaponic activity within the humanitarian sphere. In addition, small-scale aquaponic units are components of some urban or peri-urban agriculture initiatives, particularly with non-governments organizations and other stakeholders in urban food and nutrition security, because of their ability to be installed in many different urban landscapes. In particular, the Food and Agriculture Organization of the United Nations (FAO) has piloted small-scale aquaponic units on rooftops in The West Bank and Gaza Strip - in response to the chronic food and nutrition security issues seen across the region (Figure 1.10). To date, this pilot project and subsequent scale-up are one of a growing number of examples around the world where aquaponics is being successfully integrated into medium-scale emergency food security interventions. However, many attempts are ad hoc and opportunistic, in many cases leading to stand-alone, low-impact interventions, so caution should be used when evaluating the success of humanitarian aquaponics.
In the recent years there has been a surge of aquaponic conferences worldwide. Furthermore, aquaponics is increasingly a part of conferences on aquaculture and hydroponics. Many of these panels outline the raising concerns among researchers from different backgrounds and specializations, policy makers and stakeholders to find sustainable solutions to ensure a long-lasting growth and secure increased food output for a growing world population. 
Source: Food and Agriculture Organization of the United Nations, 2014, Christopher Somerville, Moti Cohen, Edoardo Pantanella, Austin Stankus and Alessandro Lovatelli, Small-scale aquaponic food production, http://www.fao.org/3/a-i4021e.pdf. Reproduced with permission.