Aquaponics – Everything You Need to Know

What Is Aquaponics

Aquaponics is a cultivation method that grows plants in combination with aquaculture, or the raising of aquatic animals like fishes and eventually crayfish, snails, shells, or prawns. It is part of the broader “soil-less” cultivation methods, including hydroponics and aeroponics.

In its modern form, aquaponics is often combined with relatively high-tech hydroponics cultivation – the cultivation of plants without soil – using water to bring them their nutrients. It can often be part of a vertical farming or indoor farming system.

We discussed in detail the different systems possible for hydroponic cultivation and its pros and cons in our article “Hydroponics – Everything You Need to Know”.

The mix of agriculture and aquaculture is however a very ancient one. Aztecs cultivated on agricultural highlands named chinampas over lakes, Chinese farmers cultivated rice with fishes in the paddies for millennia, and so were the native cultures of Southeast Asia, including the remarkable city of Angkor Wat.

Source: Prevention Web

The aquaponics market size represents nearly $1.2B billion in 2024 and is expected to grow by 9.6% CAGR until 2029. The largest markets are located in North America and Asia.

The Science of Aquaponics

Hydroponics offer very tight control over cultivation conditions, helping to grow reliably high-quality crops. It is also very water and space-efficient. But what if it could also grow very dense, healthy meat with the same water,  as well? This is made possible by connecting the water the hydroponic system uses to aquaculture growth tanks.

The strongest argument in favor of aquaponics is to form a circle in which each component solves a problem present in hydroponics and aquaculture when separated.

Hydroponics is a very efficient cultivation system but requires constant addition of fertilizer into the water to keep the plant healthy and growing.

Meanwhile, aquaculture requires a lot of fresh, clean water and filtration, as the fish's waste (or other aquatic animals) will accumulate and pollute the water.

In an aquaponic system, both get “solved”. The fish droppings are not pollution anymore, but nitrogen-rich fertilizers for the plants. Then the plant roots clean and filter the water “for free” by absorbing them.

Source: The Aquaponic Resource

Types of Aquaponic Systems

Media-Based Aquaponic System

An inert media like gravel, lava rocks, or clay pebbles anchor the plant's roots. The plant growth bed is periodically flooded with water from the fish tank through a bell siphon. This brings the nutrients to the plants.

The water is then sent back to the fish tank to close the cycle once the water has been filtered by the plants. Sometimes, worms are added to the inert media bed to help break down the fish droppings.

Source: Go Green Aquaponics

As this system uses no filter and the least component, it is the simplest.

Raft System

The plants are positioned on floating rafts, with roots dangling in the water. The nutrient-rich water from the aquaculture tank continuously flows into a filter system, and then the plant rafts.

The filter contains bacteria that help make the nutrient more “digestible” by the plants.

This system is more complex but can be scaled up much more easily, with no limit to the number of rafts or the size of the fish tank, as long as the water pipes and filter match.

Source: Go Green Aquaponics

Nutrient Film Technique (NFT)

This system is similar to the media-based aquaponic systems but with a thin film of continuously flowing water coming from the fish tank. There is no intermediary filter like in the raft system.

Source: Go Green Aquaponics

The system provides a few advantages but also limitations.

The flowing water and thin layer of water allow for rich oxygenation, beneficial to both the plant's roots and the fish, as the water then goes back into the tank. It is also very space efficient and can be used in tight spaces or tall vertical farming systems. Lastly, the continuous flow of nutrients and water boosts plant growth better than a media-based system, but without the need for the filter of the raft system.

However, NFT systems are fit only for plants with small roots, like leafy greens; larger root systems will not work well. It is also possible that the roots will clog the shallow channels, which can cause nutrient deficiency. The temperature of the water can fluctuate quickly, especially if the plants are exposed to direct sun, which can cause issues for both the plant and the fish.

What Can Be Grown With Aquaponics

Plant Side

Most plants that can be grown with hydroponics can be grown with aquaponics. The market of hydroponics is mostly dominated by high-value crops with constant demand and a need for a high-quality and controlled-growth environment:

• Tomatoes.
• Herbs.
• Lettuce.
• Cucumber.
• Peppers.

Source: Grand View Research

Other high-value crops can be grown with hydroponics & aquaponics, like for example cannabis or hops. In this case, hydroponics/aquaponics bring a high level of consistency to the growth conditions, resulting in a consistent taste & chemical composition.

Aquaculture Side

Fish Raising

The most popular aquatic animal raising is fish.

Fresh water is mandatory for aquaponic systems, as salty sea water would be toxic to the plant component of the system.

Some research is being done to develop salt-water aquaponics, looking for plants with high enough salt tolerance. The options explored include the common ice plant (a popular hydroponic crop in Japan), salt-tolerant GMO rice varieties, or seaweed.

Among popular fishes for aquaponics are:

• Tilapia (by far the most common fish in aquaponics).
• Bluegill/brim/sunfish/crappie.
• Catfish.
• Perch.
• Carp.
• Koi.
• Pacu.
• Various ornamental fish such as angelfish, guppies, tetras, swordfish, mollies, goldfish.

In general, the best fishes will have the following characteristics, also beneficial for aquaculture in general:

• Live well with each other in small, confined tanks, with small enough adult maximum size.
  • Breeding well in captivity is another valuable trait.
• Quick growth, especially for meat fish, and ideally a good feed conversion ratio (how many pounds of food is required to grow a pound of fish).
• Good resistance to diseases.
• Good tolerance of cold water (reduces the need for expensive and energy-intensive heating) and temperature variations (hard to control with seasonal changes).
  • The fish tank's temperature and the fish species should be adapted to the location.
• Strong market demand for this species.

Other Aquatic Animals

Fishes are not the only animals that can be raised with aquaponics, alternatives exist, such as:

• Crayfish/yabbies, a small freshwater relative to the lobster.
• Shrimp and Prawns, as long as they are of the freshwater type. They require rather high water temperatures.
• Mussels, Oysters & other shells
  • Shells will help keep the water clean and provide a high-value product for sale.
  • They can however cause issues if they spread and settle inside the system piping, creating clogs.
  • As shells mostly feed on microalgae and plankton, hydroponic cultivation of algae could make for an original aquaponics system without either plants or fish.
• Turtles & aquatic reptiles. Aquatic reptiles are sometimes raised as pets, or even for food in some countries. So they could play the same role as fishes in an aquaponic system, especially in a warm environment.
• Worms (“vermiponics”).
  • The worms can be fed agricultural wastes, kitchen scraps, rabbit manure, and other products that would not be working as fish feed.
  • They require less oxygen and generally are more resilient than more complex animals.

Bacteria Filter

While not all aquaponics systems use a filter, it is often required for large-scale installations.

The point of such a filter is to harbor bacteria able to convert the aquatic animal, rich in ammonia, into nitrites and nitrates (“nitrification”), more beneficial for plants.

If not turned into nitrates and used by the plants, high-concentration of ammonia (and to a lesser extent nitrite) could also kill the fishes and other aquatic animals. As plants assimilate ammonia less well, this makes the requirement for nitrification a must in many designs.

Ammonia is converted into nitrite by Nitrosomonas bacteria, and nitrite into nitrates by Nitrobacter bacteria. The process can take time, so this needs to be taken into account for the design and operation of an aquaculture system, with potentially several tanks of bacteria filters releasing the treated water sequentially.

The Pros of Aquaponics

Aquaponics share many of the hydroponics advantages (and limitations). This includes 1/6^th to 1/10^th of water consumption compared to traditional agriculture, highly consistent and productive growth conditions, lower pesticide consumption and no herbicide, and the elimination of soil-born diseases.

Aquaponics also has unique advantages on top of hydroponics or aquaculture alone:

• All natural fertilizers, entirely coming from fish waste.
  • The fish feed, anyway needed in aquaculture, is now reused “twice”, saving on the cost of fertilizers.
  • It can allow for more natural and organic hydroponic cultivation, with no chemical fertilizers entering the system.
• The fish's water is naturally filtered. This replaces the need to discharge 5 -30% of the water daily.
  • It dramatically reduces the aquaculture water usage.
  • It also reduces aquaculture-related pollution, which can result in damage to nearby water sources, as well as toxic algal blooms and freshwater bodies' eutrophication.
• Produce both protein-rich food and healthy plant products at the same time.
• Diversified income source.
  • Vegetable and fish market prices can fluctuate widely but without being correlated with each other.
  • Fish harvest is less regular but can provide a large cash influx on top of the more regular hydroponic cultivation income.

The Cons of Aquaponics

While overall more efficient than both hydroponics and aquaculture separately, aquaponics can present its own set of challenges.

Complexity & Costs

While cost was already the main limitation of hydroponics, aquaponics is even more complex and therefore costly to set up. Aquaculture systems have now been added to the hydroponic systems.

Each needs to be sized so they exactly match each other so that there are enough plants to filter the water, as well as enough fish to provide enough fertilizer.

This more complex system also needs to manage temperature well, both air temperature and water temperature, with evaporation and average humidity to be taken into account as well. And both plants and animals can modify the water pH, which can reduce growth or even kill them if out of balance.

Control & Skills

Because of the interconnection of all the parameters to monitor, constant supervision and sensors are required to check these metrics.

Similarly, monitoring for outbreaks of diseases now needs to be done for both fish and plants. Treating them can be more difficult, with for example giving antibiotics to the fishes potentially leading to contamination of the plants, or fungicide for the plant contaminating the fish meat.

The monitoring and care for such a complex system requires good knowledge and training, even more than what is required for “simpler” hydroponics or aquaculture alone, which are rather complex fields in agriculture.

Energy Demand

Temperature variations can be deadly for aquatic animals, even quicker than for plants with less tolerance for large or quick changes.

So an aquaponics system will likely require a heating and/or cooling system to keep the water in an acceptable range.

This can make aquaponics very energy-intensive, especially in some climates. It can also complicate the usage of natural light and greenhouses for the plant component of the system. While this reduces the need for artificial lights and warming of the plants, it can also lead to overheating of the water in the summer months, which can easily become a problem for aquatic animals.

Resilience

Aquaponic systems are by nature very artificial. They require a lot of piping, pumps, sensors, filters, etc. This means they are depending on everything running smoothly:

• Supply chain in parts and components.
• Electric power supply.
• Electronic connected system for highly automated and advanced operations.
• Skilled labor able to perform efficiently the required monitoring and maintenance.

These issues are even more pronounced than with hydroponics as fishes will need a constant supply of feed, filtered water, and oxygen.

So the aquaponics system going offline for just 24 hours could mean the death of all the fish, something that could probably have been tolerated by the plants alone.

While there are ways to mitigate these risks, for example with systems redundancy or larger inventory (which adds to setup costs), or localized supply of energy through renewable power generation, aquaponics will never be as resilient as hydroponics, and way less than a rain-watered crop in an open field.

Innovation in Aquaponics

Aquaponic Innovation

As Aquaponics combines both hydroponics and aquaculture, innovations in both of these fields can improve productivity.

Hydroponic Innovations

LED Lighting

LED lights are another crucial technology intervention in hydroponics and aquaponics. These lights consume far less energy, emit less heat, and last longer than other light sources.

In addition, not all the visible light spectrum is useful for plants in photosynthesis, so dedicated LEDs without green light can be used to reduce further the electricity consumed by artificial lightning.

Source: Agritecture

eSoil

Hydroponic cultivation allows for direct control over plants in a way impossible in traditional farming. This opens the door to experimentation for new ways to boost crop productivity beyond increasing access to light or nutrients.

For example, we explore one such option in our article “Electricity Set to Supercharge Growth in Hydroponic Crops”. Researchers used a custom artificial substrate, or “conductive soil / eSoil” made of cellulose (the main component of paper) mixed with a conductive polymer called PEDOT (poly(3,4-ethylenedioxythiophene)). This way, they could expose seedlings to continuous low voltage, resulting in a 50% increase in growth rate.

This is but one example of how hydroponic systems could offer significant productivity gain thanks to the increased level of control they offer.

Aquaculture Innovation

One of the major issues in aquaculture is pest and disease management. Biotechnology progress makes possible the idea of using RNAi treatments to reduce the impact of viruses like for example the white spot syndrome virus (WSSV), a virus that has a significant negative impact on aquacultured shrimp.

Vaccines could also be delivered with the food of the fishes, either through special micro-encapsulation or even using genetically modified algae forming an edible, self-replicating vaccine.

Lastly, with wild fish stocks being quickly depleted, highly reliable sourcing methods using blockchain solutions like Fishcoin can be used to ensure that fish meat reaching consumers has been produced in the most ethical way and with the lowest energetic cost.

Other high-tech solutions might be used as well, such as individual fish monitoring sensors, like the iFarm, which was developed in collaboration between the salmon farm Cermaq in Norway and sensor company BioSort.

Innovation For Both Hydroponics & Aquaculture

IoT & Sensor-Based Automation

The declining costs of sensors and electronics have made possible the continuous monitoring of temperature, humidity, light, pH levels, and nutrient volume. This level of monitoring is even more important than with hydroponics as the presence of animals makes unwanted variation more likely and has more serious consequences.

This sensor-based method helps to track and adjust in real-time that the conditions stay constantly optimal.

AI-Based Technologies

As mentioned, aquaponics requires an extremely intense level of monitoring of the water system, diseases, nutrient levels, temperature, pH, quality of the filtering, etc.

AI can help optimize existing environmental conditions, including light levels, humidity, and nutrient levels. AI also helps optimize investment and bring down costs by creating custom solutions to specific conditions. Over time, this could reduce the requirement for human operators to be highly trained and knowledgeable about aquaponics.

AI can also use machine vision or regular automated biochemical tests to warn about the presence of diseases before a human can.

Lastly, with the rise of autonomous farming robots, we can envision a aquaponic system where planting, pruning, harvesting, and replacing plants, as well as feeding, breeding, and harvesting the fish, can be done autonomously by the AI controlling the aquaponics system.

Launching An Aquaponic Installation

It will also need a slow initiation phase, which will be necessary to get a balanced and stable nitrogen cycle. Before adding fish, it is best to establish the nitrogen cycle by introducing ammonia into the system and letting the bacteria biofilm grow inside the filter so that ammonia will be efficiently converted into nitrites and nitrates.

The same is true for adding fishes and plants, with progressive introductions allowing for adjusting water quality parameters, fish feeding and plant growth. Only once the system is running smoothly with plants and animals at different stages of growth and continuous harvest can the aquaculture system be considered to be fully set up.

Sizing

Because of the complexity of aquaponics, most of these systems tend to be built at a commercial scale with a precise return on investment expected. They will also tend to integrate a high degree of automation and sensor technologies.

This does not mean that more manually controlled or smaller systems cannot be built, but they might be harder to keep in balance regarding acidity, temperature, ammonia levels, etc., and require more punctual adjustments.

The sector is still in its early stages, with no standardized template and a lot of experimentation. It is, however not just a concept in development anymore, with some notable large installations:

• Superior Fresh in Wisconsin, since 2017, has grown annually 1.8 million pounds of lettuce and leafy greens — and 40,000 pounds of fish — within 123,000 square feet of production space (11,000+ square meters).
• Les Nouvelles Fermes in France, which raised $2M in 2020 to produce 60 tons of fresh produce and 12 tons of rainbow trout annually.
• Jabber Al Mazroui's 4,000 square meters of aquaponic installation in the United Arab Emirates.

Conclusion

Aquaponics is a remarkably efficient design, solving many of the limitations of both current hydroponic and aquaculture methods. It can reduce both the dependency of hydroponics on chemical fertilizers and the water pollution and waste caused by aquaculture.

It is however a lot more technical, and most people and companies will likely benefit from first developing extensive experience in working in at least either hydroponics or aquaculture before working on combining them together with aquaponics.

This way, they will be more likely to succeed in handling the multiple challenges posed by the complexity of the system, like diseases & pest management, chemical imbalance (pH, ammonia levels, etc.), species selections, temperature fluctuations, etc.

Nevertheless, considering the global population growth combined with depleting wild fish populations & decline in arable land surface, aquaponics could be a powerful solution to produce high-quality plant products and high-protein healthy meat. And doing so with lower use of land and water, while emitting much less pollution.