Aquaponics is a food production system that couples aquaculture (raising aquatic animals such as fish, crayfish, snails or prawns in tanks) with hydroponics (cultivating plants in water) whereby the nutrient-rich aquaculture water is fed to hydroponically grown plants.
Plants are grown in hydroponics systems, with their roots immersed in the nutrient-rich effluent water. This enables them to filter out the ammonia that is toxic to the aquatic animals, or its metabolites. After the water has passed through the hydroponic subsystem, it is cleaned and oxygenated, and can return to the aquaculture vessels.
The size, complexity, and types of foods grown in an aquaponic system can vary as much as any system found in either distinct farming discipline. The main fish grown in aquaponics are tilapia, koi, goldfish, carp, catfish, barramundi, and different types of ornamental fish. The main plants produced include lettuce, pak choi, kale, basil, mint, watercress, tomatoes, peppers, cucumbers, beans, peas, squash, broccoli, cauliflower, and cabbage.
Fish, plants and microbes are three main components of aquaponics, and microbes play the bridge role of converting fish waste to plant nutrients. The three major types of modern aquaponic designs are deep-water or "raft", nutrient film technology, and media-based bed or reciprocating systems.
System types Generally, aquaponics systems are classified into three types, namely media-based grow bed, deep water culture/floating raft, and nutrient film technique. Among them, the media-based system is believed to be more efficient in the utilization of nitrogen.
Media-based grow bed
A media-based grow bed is a hydroponic system type that utilizes a trough filled with an inert material to assist plant roots and accommodate beneficial microbes. Water is usually delivered in a flooding and draining cycle (ebb and flow), delivering nutrients and oxygen to the plants.
By utilizing gravel or sand as plant supporting medium, solids are captured and the medium has enough surface area for fixed-film nitrification. The ability to combine biofiltration and hydroponics allows for aquaponic system, in many cases, to eliminate the need for an expensive, separate biofilter.
A media‐based system is believed to be more efficient in the utilization of nitrogen since it provides more volume‐to‐surface area ratio for the microbes than deep-water raft or nutrient film technique.
Deep water culture
The deep water culture system consists of substantial troughs containing perforated floating rafts, into which net plant pots are placed. Within the system, these plant pots are typically filled with media, such as rockwool, coco, or pumice, that serve to support the roots, which are subsequently and continuously submerged within the water tank.
Nutrient film technique
The nutrient film technique consists of narrow channels of perforated squared pipes where the roots are partially immersed in a thin layer of streaming water.
History
Aquaponics has ancient roots, although there is some debate on its first occurrence.
Early beginnings: Aztecs and Chinese (6th century - 13th century)
Aquaponics has been said to have evolved from relatively ancient agriculture practices associated with integrating fish culture with plant production, especially those developed within the South East Asian, flooded rice paddy farming context and South American Chinampa, floating island, agriculture practices (Komives and Junge 2015). In reality, historically, fish were rarely actively added to rice paddy fields until the nineteenth century (Halwart and Gupta 2004) and were present in very low densities which would not contribute to any substantial nutritive assistance to the plants. Chinampas were traditionally built on lakes in Mexico where nutrient advantages may have been supplied via the eutrophic or semi-eutrophic lake sediments rather than directly from any designed or actively integrated fish production system (Morehart 2016; Baquedano 1993). The Aztec cultivated agricultural islands known as chinampas in a system considered by some to be an early form of aquaponics for agricultural use, where plants were raised on stationary (or sometime movable) islands in lake shallows and waste materials dredged from the Chinampa canals and surrounding cities were used to manually irrigate the plants. South China and the whole of Southeast Asia, where rice was cultivated and farmed in paddy fields in combination with fish, are cited as examples of early aquaponics systems, although the technology had been brought by Chinese settlers who had migrated from Yunnan around 5 AD. These polycultural farming systems existed in many Far Eastern countries and raised fish such as the oriental loach (泥鳅, ドジョウ), swamp eel (黄鳝, 田鰻), common carp (鯉魚, コイ) and crucian carp (鯽魚) as well as pond snails (田螺) in the paddies. The 13th-century Chinese agricultural manual Wang Zhen's Book on Farming (王禎農書) described floating wooden rafts which were piled with mud and dirt and which were used for growing rice, wild rice, and fodder. Such floating planters were employed in regions constituting the modern provinces of Jiangsu, Zhejiang, and Fujian. These floating planters are known as either (架田) or (葑田), which translates to "framed paddy" and "brassica paddy", respectively. The agricultural work also references earlier Chinese texts, which indicated that floating raft rice cultivation was being used as early as the Tang dynasty (6th century) and Northern Song dynasty (8th century) periods of Chinese history.
Modern developments (1930s-present) An integrated system of aquaculture and agriculture where fish are grown in rice paddies has been employed in the North Kerian area of Perak in Peninsular Malaysia since the 1930's. Several rice-fish systems are also reported to have a long history in Indonesia.
In 1965, Sengbusch and his colleagues were the first to attempt raising common carp, a type of fish, in tanks with a system that recirculated water and used activated sludge to treat the water. A few years later, in 1971, Scherb and Braun provided more detailed studies on using a similar system to raise rainbow trout. At the South Carolina Agricultural Experiment Station in Clemson, researchers Loyacano and Grosvenor (1973) tried to clean fish ponds with channel catfish by using water chestnut plants to absorb the extra nutrients.
In 1977, German scientist Ludwig C.A. Naegel contributed to the field of aquaponics with his publication 'Combined Production of Fish and Plants in Recirculating Water.' The work presented experiments on the co-cultivation of tilapia and tomatoes, showcasing the practicality of a recirculating system that supports both fish and plant production. This research is among the efforts by a global community of researchers to develop modern aquaponics systems.
Balarin and Haller conducted studies on the thermal dynamics of aquaponic systems, examining the effects of varying water temperatures on the growth rates of fish and plants.
In the development of biofiltration techniques within aquaponics, Muir, Paller, and Lewis introduced reciprocating biofilters (RBFs). These biofilters enhanced the efficiency of nutrient uptake by plants and reduced the accumulation of harmful metabolites in the water.
Watten and Busch contributed to the understanding of nutrient dynamics in aquaponic systems. Their studies on the integration of vascular plants into recirculating aquaculture systems (RAS) demonstrated how plants could effectively extract excess nutrients from the water.
Prior to the technological advances of the 1980s, most attempts to integrate hydroponics and aquaculture had limited success. Many of the modern developments and discoveries of aquaponics are generally attributed to the New Alchemy Institute and North Carolina State University.
New Alchemy Institute In 1969, John and Nancy Todd and William McLarney founded the New Alchemy Institute and built a prototype replica of the Aztec's aquaponic system (with some modifications) to provide shelter, vegetables, and fish throughout the year. In 1984, Ronald Zweig of the New Alchemy Institute developed a system he called the 'hydroponic aquaculture pond,' also referred to as a 'hydroponic solar pond.' This system integrated a floating hydroponic component within the institute's existing solar pond these floating raft systems are the foundation for what became later known as deep water culture.
North Carolina State University Mark McMurtry and others at North Carolina State University conceptualized the Integrated Aqua-Vegeculture System. This system, which integrates aquaculture with sand-based grow beds, represents one of the earliest instances of a closed-loop aquaponic system. McMurtry's research and findings confirmed much of the foundational science underlying aquaponics, demonstrating that the system operates effectively.
University of the Virgin Islands In 1979, James Rakocy and his colleagues at the University of the Virgin Islands began experimenting with media beds in aquaponics. Initially, the system utilized a gravel bed for plant growth, alongside a conical filter settling tank to collect larger solid waste, and a separate tank for housing the fish. In 1986, they started to test the use of floating rafts constructed from polystyrene. By 1997, Rakocy's research had led to the adoption of deep water culture hydroponic grow beds in large-scale aquaponic systems.
Other systems Other institutes focused their research on systems known as "ebb and flow," or "flood and drain" systems. These systems utilize coarse media like gravel or expanded clay, with bell siphons facilitating the irrigation cycle These systems are sometimes referred to as "Speraneo Systems," as they were named after Tom and Paula Speraneo, who created and sold an instructional manual in the 1990s and adopted the North Carolina State University system to invent a full-size commercial-scale solar greenhouse.
The first aquaponics research in Canada began with a small system integrated into aquaculture research at a station in Lethbridge, Alberta. In the 1990s, commercial aquaponics setups increased, focusing on high-value crops like trout and lettuce. A key development occurred in Brooks, Alberta, where Dr. Nick Savidov and his team from Lethbridge College's Aquaculture Centre of Excellence (ACE) conducted extensive research. They found rapid root growth in aquaponics systems and effective methods for closing the solid-waste loop. They also discovered that these systems could efficiently operate at low pH levels, which benefits plant growth but is typically unfavorable for fish. This research led to the creation of the first fully automated zero-waste aquaponics system, enhancing sustainability and efficiency in aquaponics operations.
Floating aquaponics systems on polycultural fish ponds were installed in China in 2009. They are used to grow rice, wheat and canna lily and other crops, with some installations exceeding .
Terminology The term "aquaponics" combines "aquaculture" (the farming of aquatic organisms) and "hydroponics" (the soilless cultivation of plants).
In the 1970s and 1980s, aquaponics was described by various terms such as "combined fish and vegetable production in greenhouses" or "combined production of fish and plants in recirculating water." The term "aquaponics" became more widely used after the Aquaponics Journal began publication in 1997, although other terms like "integrated fish/vegetable co-culture system" were also used.
Definitions of "aquaponics" vary. Some experts limit it to plant cultivation using hydroponics, while others have a broader interpretation. The suffix "ponics" in hydroponics and aquaponics comes from the Greek word "ponos," meaning "work." Therefore, "aquaponics" can be translated to "water work," though this may not fully describe the system's function and purpose.