Aquaponics refers to the integrated production of aquatic animals and plants, using the same water resources and nutrient inputs. In modern times, aquaponics are practiced within recirculating systems. Although it was probably already being practiced for centuries at the time, the first written record of aquaponic methods was published by Fan Lai in China in 500 BC. In the following centuries, the practice was adopted in other parts of eastern and southern Asia, but aquaponics may have arisen independently in a number of regions, since there are historical records of this form of integrated plant and fish culture from Japan, Peru, Egypt, Greece and Mexico.
Mayan and Aztec cultures developed aquaponic methods before 1000 AD. They created artificial planted rafts called chinampas in lakes and ponds, with plant roots extending into the water below the surface. The ancient Aztec capital Tenochtitlan was established in the middle of a large, shallow lake, and by some estimates crops such as corn, beans, squash, peppers and tomatoes grown on chinampas may have provided one-half or more of the city’s food supplies.
Although some accounts credit researchers at North Carolina State University for pioneering modern aquaponics in the 1980s, the first example of a modern coupled system was actually developed in Germany and described by Naegel in 1977. Aquaponics systems are water and energy efficient, geographically adaptable and capable of producing a variety of plants and fish species.
An intermediate-scale pre-commercial aquaponic system.
Proponents of aquaponic systems often cite a number of benefits associated with this form of farming. These systems are environmentally friendly, recycling most water and nutrients throughout the production cycle. In some cases, aquaponic production uses only 10% as much water as traditional crop production on cultivated land. With good management, the use of chemicals, pesticides and synthetic fertilizers can be greatly reduced or eliminated. If space is available, aquaponics systems can be easily scaled up to meet market demands.
There are also some inherent constraints involved in aquaponics. The practice is often classified as labor and management intensive. Water quality, fish health and plant pathogens must be monitored on a daily basis. Temperature regulation can be time consuming and expensive, especially if operations continue year-round and through the winter. System components can be expensive, either to purchase or to construct. All the normal components of a recirculating system for fish production must be present in an aquaponics system, including solids removal and biofiltration must be present in an aquaponics system in one form or another, and high quality makeup water is required daily. Some fish species can be difficult to raise to market size in aquaponic systems, and treating diseases and pests can result in toxicity issues and delayed harvests due to required withdrawal times for treatment compounds to break down to safe levels.
In the U.S. industry, tilapia are probably the most adaptable fish species for use in most aquaponics businesses. Other fish are generally less suited for various reasons. Catfish are disease prone under high density conditions, but they require high densities in cages or tanks to deter the formation of aggressive hierarchies. Carp can adapt to aquaponic conditions, but they are not a sought-after species in U.S., and most other aquatic species – even where allowed by state resource agencies – grow too slowly or are too carnivorous for profitable production. Some success has been reported with hybrid bluegill, freshwater prawns and red claw crayfish, and successful culture has been reported with trout in some cool-water situations so these species may bear evaluation in the context of the geographical region and target markets in question. However, some fish species such as hybrid striped bass simply do not tolerate the typical aquaponics environment – especially when plant nutrients must be supplemented.
Whatever the species, the efficiency of fish production in a recirculating system depends on maximizing the average standing crop from day to day. In an aquaponic system this can be accomplished by holding different “batches” of fish in separate net-pens (which can be configured to be enlarged as the fish grow by gradually unrolling excess netting affixed to one end of the pen), or by operating aquaponic systems in groups of three, with one system designated for nursery rearing and the other two for final grow-out.
One example of a commercially-available channel system used in Nutrient Film Technology (NFT); note the down-slope oriented channels and the common out-flow return collector.
The plant-production components of aquaponics systems generally fall into three categories: media beds filled with gravel or clay pellets, deep water culture (DWC) trays or tanks with floating rafts (the most common and lowest cost option), and nutrient film technique (NFT) plastic channels with constantly circulating water to provide nutrients to the plant roots.
Plan on developing the infrastructure and expertise to produce your own transplants, even if suppliers are available. Using transplants saves time, space, and energy, and is based on the same logic as multiple-phase grow-out production strategies found in most types of aquaculture. Transplant varieties should be suitable for greenhouse conditions, as opposed to outdoor home gardens. Most greenhouse-adaptable seeds produce hybrid plants that are disease resistant and can thrive under reduced light levels.
Tomatoes, lettuce, herbs, marijuana, peppers, watercress, lettuce, leafy greens, squash, zucchini, cucumber, peppers, eggplant, are all examples of plant crops that have been raised successfully in aquaponics. However, rapid turnover of plant crops is important to generate profits and maintain cash flow. Romaine lettuce, spinach, kale, herbs and several other types of plants grow quickly under aquaponic conditions and are well suited for this strategy. Diversifying plant crops makes sense and can result in more marketing options, but plant crops must be compatible in terms of temperature and humidity requirements if they are to be produced simultaneously in the same system. In some cases, it may be necessary to supplement certain plant nutrients such as potassium, iron or even calcium. Insect pests are a threat to some plant crops, and early detection and control are essential.
Integrating fish and plant production results in efficient use of resources, and synergistic effects in terms of converting inputs into marketable products. Labor, electricity/heating and other primary expenses can be designated for both crops, but this approach requires maintaining the system in balance while monitoring and caring for both plants and fish. For both plant and fish production, supplemental lighting and heating will be required in most regions of the U.S., even in the deep South from time to time.
Food safety has emerged as an extremely important management consideration in aquaponic systems. Systems and produce should be routinely tested for E. coli. The need to maintain healthy populations of beneficial bacteria in biofilters and throughout recirculating systems results in a limited number of options for avoidance of potentially harmful bacteria such as E. coli. As a result, a number of key areas of focus must be addressed on a day-to-day basis in order to maintain food safety. These are fairly straightforward: limiting the presence of warm-blooded animals (birds, mice, rats and cats) and their feces, maintaining pollution-free water sources, sanitation practices for staff on site and proper harvesting practices. Cold-blooded aquatic animals such as fish, crustaceans and insects do not typically harbor E. coli but some frogs and turtles can carry Salmonella, especially in warmer regions. Rather, the bacteria gets into the system from outside sources and can persist there without a suitable host for some amount of time.
If E. coli is picked up in system water it does not necessarily mean the produce and fish are contaminated, but it is cause for concern and a good excuse to review the facility’s structural access for rodents or birds and the operating practices of the staff. Foot baths at entrances and exits are important to limit potential contamination from outside the facility. A set of rubber boots should be available for each worker, with bleach in the foot baths and a spray bottle of bleach for washing the boots at entry and exit. Hands can be sanitized with an atomizing spray of rubbing alcohol.
Before plants and vegetables are harvested, hands and forearms should be double washed (to the elbows), rinsed thoroughly and dried with disposable paper towels. An atomizing spray bottle of rubbing alcohol should be used to moisten hands thoroughly, or disposable gloves should be put on after washing hands. This must be repeated after touching fish or even the system water. In fact, any contact with anything (including food) or anyone (including other workers) requires hands to be washed again. Protective, disposable gloves should be used whenever fish or soil will be handled. When using floating rafts to grow the plants (DWC), special care must be taken during harvest to avoid contaminating the plants with the slime on the sides and bottom of the raft, since potential food-borne illnesses can persist on these surfaces.
The Australian Red-Claw Crayfish is an example of a crustacean that can be reared alone or with fish in an aquaponic system.
When considering the profitability of any aquaponics business, the optimal system design, most profitable fish species and candidate plant species will all depend on the target market(s). Consider the consumers to be targeted, what their preferences are and what they are willing to pay for the products the business will be producing. These potential market prices must then be evaluated in light of production costs.
Production costs will involve both investment and operating costs. Investment costs involve everything from land, to greenhouse structure, to site preparation, to production systems, to lighting and heating equipment, to electrical installation and emergency generators, etc. etc. etc. Operating costs will be dependent on production volume, and these costs will typically include fingerlings, fish feed, energy, fuel, pest control, fertilizer, seeds, disposable materials for transplant production and similar costs. Keep in mind that in most situations, some portion of production will go unsold.
Prospective aquaponics producers must consider exactly what will differentiate their products (both fish and vegetables) sufficiently to justify higher costs in the marketplace. It is difficult to market locally grown produce in rural areas, but most urban populations have a segment willing to pay for high-quality, fresh, locally grown products. The question during the planning process is - how many of these people are out there and how much are they willing to pay? The aquaponic product attributes of ‘locally grown’, ‘fresh never frozen’, ‘sustainably farmed’ and, in some cases, ‘organically grown’, are essential to overcoming price differentials when compared to commodity-based products in local supermarkets.
Aquaponic facilities can be located in urban food deserts, or peri-urban areas that attract affluent clientele. Both of these strategies can provide for marketing opportunities. At harvest, all vegetables and herbs must look appealing and be of the highest quality. Whether small- or medium-scale, or larger, growing fish and plants is only part of any aquaponics business. Harvesting, packing, distribution, marketing and all other operational aspects become more difficult as operations get larger, because economies of scale are not as impactful in aquaponics as in other forms of aquaculture.
In general, aquaponics operations have a better chance of profitability in regions where fresh produce and fish are in limited supply or where a significant segment of the population can pay a premium for high-cost fish and produce. Farmers’ markets, specialty grocers, restaurants and direct-to-consumer sales are all potential market outlets for aquaponics producers. Many business-scale customers will insist on product liability insurance, so food safety considerations must always be a management focus and a marketing advantage. As in any form of aquaculture, selling to a number of smaller buyers increases marketing and distribution costs significantly, but reduces the risks associated with the loss of any one customer.
Sustainable landscape construction. Aquaponics. https://depts.washington.edu/dislc/2012_winter_aquaponics/introduction.htm U.W. Dept. of Landscape Architecture.
Recirculating Aquaculture Production Systems: Aquaponics Integrating Fish and Plant Culture. https://srac.tamu.edu/fact-sheets/serve/105 Southern Regional Aquaculture Center.
Economics of Aquaponics. https://srac.tamu.edu/fact-sheets/serve/282 Southern Regional Aquaculture Center.
Principles of Small-Scale Aquaponics. http://srac.tamu.edu/fact-sheets/serve/284 Southern Regional Aquaculture Center.
Controlling the Greenhouse Environment for Aquaponics. http://srac.tamu.edu/fact-sheets/serve/290 Southern Regional Aquaculture Center.
Greenhouse Crops and Cropping Systems for Commercial Aquaponics. https://srac.tamu.edu/fact-sheets/serve/289 Southern Regional Aquaculture Center.
Building a Simple At-home Aquaponics System. https://srac.tamu.edu/fact-sheets/serve/286 Southern Regional Aquaculture Center.
Vegetable Transplants in Aquaponics Systems. https://srac.tamu.edu/fact-sheets/serve/294 Southern Regional Aquaculture Center.
Prepared by C. Greg Lutz, Louisiana State University Agricultural Center