Aquaponics mimics a natural ecosystem in miniature form, following the same processes that occur in aquatic environments. To begin, the fish become active participants by eating and excreting, which produces nutrient-rich water – thanks to the fish poop! Next, bacteria come into play to transform the fish waste into an optimal fertilizer for plant cultivation. The plants, in turn, absorb this fertilizer through their roots and purify the water as a result. The clean water is then reused for fish farming, and the cycle repeats itself.
An aquaponics system is characterized by the mutual assistance of fish, plants, and bacteria. This combined effort permits cultivators to harvest both fish and vegetables using the same volume of water that would typically be employed to obtain only a single product. Rather than wasting water, this loop operates continuously with hardly any wastewater discharged into the environment.
Aquaponics, Past and Present
Aquaponics has a long history dating back to approximately 1,500 years ago in South China, Indonesia, and Thailand where paddy fields were utilized to grow rice alongside fish. This method made use of fish waste as a natural fertilizer for the rice.
Another form of aquaponics was developed by a group of people in central Mexico, 500 years after the previous invention. This group, known as the Aztecs, established a vast empire and built their capital, Tenochtitlán, on the shores of Lake Texcoco. Despite the wetland surroundings, the Aztecs did not have fertile land to grow their food. As a solution, they constructed floating gardens in the lake, known as chinampas, using mud and dried plant remnants. On these floating islands, maize, squash, tomatoes, and other crops were grown by farmers. The plants thrived on the nutrients from the fish waste-rich lake water.
Despite its ancient concept, it was not until the 1970s that scientists realized aquaponics’ potential. Nowadays, aquaponics is highly advanced and offers a sustainable solution to agriculture that minimizes the use of natural resources. Compared to traditional agriculture, aquaponics uses up to 90% less water and promotes faster plant growth. Moreover, aquaponics curbs pollutants generated from tractors and field chemicals.
Types of Aquaponics
Currently, there are three primary aquaponics systems in use. The first is the raft system. This method involves placing plants in drilled holes on floating rafts in tanks filled with fish wastewater. The roots of plants absorb nutrients from the water. This system is ideal for small plants like basil, spinach, salad greens, and chard. The second system is the substrate method, where plants grow in pipes with continuously flowing fish effluent water. The plants are supported by a substrate that mimics soil and helps bacteria filter the water. This method is suitable for most types of plants, including onions, tomatoes, carrots, and broccoli. The third method is the channel system, where plants are placed in a substrate that mimics soil within narrow pipes. Wastewater from the fish flows through the pipes, and the roots absorb nutrients. This system is particularly effective for plants that require less support, such as herbs, leafy greens, and strawberries. Pipes can also be positioned vertically to save space.
The Best Fish for Aquaponics 2023
Although edible leafy plants like basil, cabbage, and lettuce are more economically viable, the fish inhabiting an aquaponic setup can either be consumed or not. If you are interested in the aesthetic potential of aquaponics, you may also prefer using ornamental fish. Ultimately, the selection of fish species must be based on their capacity to thrive in dense tank conditions and their resilience to fluctuating water conditions.
Here are some commonly raised fish in aquaponic systems that are highly durable and able to resist various diseases, making them ideal for growth in recirculating water. When planning your system, be sure to choose fish that are indigenous to your region and consult your state’s invasive species register.
1) Tilapia (Cichlidae spp.)
Aquaponic systems are well-suited for raising tilapia due to their ability to adapt to various conditions. These durable fish are recognized for their immunity to diseases, overcrowding, and insufficient oxygen levels that would impact other fish species. The majority of tilapia species can flourish on a varied diet consisting of both plants and live foods. They are classified as warmwater fish and prefer a tank temperature range of 27 – 30?C (82 – 86?F), but can endure temperature drops of up to 12.8?C (55?F).
Tilapia are known for their quick rate of growth and tendency to reproduce frequently, which can either be advantageous or problematic in an aquarium. While these fish are considered suitable for beginners, it’s crucial to collect them often to prevent overpopulation. Assuming the settings are right, you could gather tilapia from your tank every six months. Luckily, they are very palatable and can be extremely appetizing if cooked properly.
2) Catfish (Clariidae, Ictaluridae, and Plotosidae spp.)
There are certain kinds of catfish that are ideal for those new to aquaponic systems. These types consist of Tandanus tandanus (eel-tailed catfish), Ictalurus punctatus (channel catfish), Ameiurus nebulosus (brown bullhead catfish), and Clarias gariepinus (African catfish). These species are quite resilient and can endure low levels of oxygen, along with drastic changes in temperature and water alkalinity.
Catfish are commonly stocked in higher densities than other fish due to their ability to tolerate high levels of ammonia thanks to their bottom-feeding habits. Their non-territorial and sociable behavior means that they do not require personal space and are comfortable in close proximity to one another. It is advisable to raise them in wider tanks rather than taller ones to provide them with the horizontal space they prefer for scavenging at the bottom of the tank.
Opting for catfish is advisable if you have apprehensions about the power provision in your locality. When it comes to catfish, the need for mechanical filtration needn’t be uniform, especially if they are raised in minimal densities. However, it is imperative to be mindful of the temperature. Since most catfish are warmwater organisms, their temperature preferences are akin to tilapia, i.e., between 24-30?C or 75-85?F.
3) Barramundi (Lates calcarifer)
Is it possible to keep a barramundi, also known as Asian sea bass, in an aquaponic setup that involves saltwater? This species is catadromous and typically inhabits freshwater throughout its life, only entering saltwater environments to reproduce. Unlike tilapia or catfish, barramundi is sensitive to water conditions and may necessitate the assistance of an aquaponics professional with prior experience.
Despite the difficulties, raising barramundi can be very satisfying, as this type of fish is renown for its rapid growth and exceptionally nutritious flesh. With appropriate conditions, barramundi can reach a harvestable size within just over five months. To guarantee their swift growth, it is essential to calculate the stocking density of your tank with care, as each barramundi needs up to 20 gallons of water volume, especially if aimed at achieving their maximum size of 0.6-1.2 meters.
For barramundi to flourish, water temperatures between 23 – 30?C (74 – 86?F) are recommended. In colder climates, the tank should have dependable water heaters. Alternatively, barramundi can be grown during warm spring or summer months and harvested when they reach a weight of approximately 500 grams. To aid in their rapid growth to this size, high-protein foods like worms, beef hearts, small fish, and shrimp can be fed to this predatory species.
4) Koi (Cyprinus rubrofuscus)
If your main concern is breeding fish for decorative reasons, you can opt for raising koi in an aquaponic setup. These valuable fish will need a spacious container (e.g. 200+ gallons for each one) with a sufficient depth. In contrast with several non-decorative aquaculture species, they might require more cleansing and elevated levels of dissolved oxygen.
Koi fish are extremely versatile and can easily acclimate to their environment, making them less susceptible to infections and infestations. They can also flourish in close proximity to each other, as long as they are provided with the necessary conditions for their well-being. Those living in cooler regions may find this species suitable as they can withstand low temperatures; however, it is important to note that maintaining their water temperature above 18?C is crucial for optimal development.
Koi are a valuable investment due to their potential lifespan of up to 35 years in captivity. Nevertheless, as they increase in size, they will require more food and produce a larger waste amount. It is crucial to take this into account, as a tank that is not appropriately sized and lacks proper filtration can have a harmful effect on your system. If you can manage to cultivate large koi in an aquaponics system, it would undoubtedly make for a remarkable display!
5) Goldfish (Carassius auratus)
If you desire a visually attractive aquaponics system but cannot meet the requirements of koi, you can raise goldfish instead. There are many different types to choose from, and an average-sized aquaponics tank can accommodate over a dozen varieties of goldfish. This will undoubtedly make your system visually appealing without the high cost associated with a koi tank.
Goldfish typically reach a maximum length of 6 inches in large tanks, but they can grow larger in the wild or in outdoor ponds. However, in a standard aquaponic system unit, they will stay small. They are a low-maintenance species that can survive in slightly polluted environments. Goldfish are rugged aquatic creatures that can adapt to pH variations and produce nutrients that are beneficial to plant growth. To maintain balance, the number of goldfish in your tank depends on the filtration capacity of your plant tank.
Goldfish will do well in colder regions and require cooler temperatures to thrive. If you cannot move your tank indoors during winter, a standard heater will work as long as it maintains the water temperature above 15?C (59?F). Opt for more resilient goldfish breeds, such as comet, common, wakin, shubunkin, and watonai, instead of ornamental varieties if you need to keep your tank outside throughout the year.
6) Perch (Percidae & Terapontidae spp.)
Aquaponic systems can easily accommodate various species of perch including yellow perch (Perca flavescens), silver perch (Bidyanus bidyanus), and jade perch (Scortum barcoo). A significant benefit of raising perch in a tank is their incapability of breeding in captivity, except for those in closely monitored hatchery systems. Despite their fast growth rate, you need not fret about tank overcrowding. By only harvesting a moderate amount, you can guarantee a satisfactory amount of nutrient-rich waste is available for your plants.
Perch are able to be raised at high densities because of their schooling behavior. They can withstand high levels of ammonia and drastic changes in pH. Herbivorous or omnivorous diets are possible, depending on the species. In their natural habitat, perch are typically low on the food chain. Fish feeds provide adequate sustenance for most species and, when properly nourished, perch can produce meat containing high levels of omega fatty acids.
Within a year of being cultured, perch can reach their maximum size. When raised in captivity, these fish typically do not surpass 10 to 15 inches in length. They are able to tolerate temperatures ranging from 17 to 28 degrees Celsius, which is cooler than what is necessary for raising tilapia. If you have access to a greenhouse for your aquaponics setup, perch would make an excellent choice for your fish tank.
7) Rainbow trout (Oncorhynchus mykiss)
An extremely attractive fish that just happens to be edible? Rainbow trout are highly sought-after game fish that can thrive in an aquaponic system. They can be reared in areas that experience cooler winter temperatures that dip to 13?C (56?F). If located in an area that experiences extremely hot summers, it is likely your set-up will have to be moved indoors. Rainbow trout struggle to survive in warm temperatures that exceed 20?C (68?F).
There are various options of food that can be provided to rainbow trout. For those raised in captive conditions, they can sustain themselves with a synthetic diet consisting of feeds made from grains. Nevertheless, if you rear them in an aquaponic setup, it would be advantageous to provide them with a food source rich in protein. This would result in a quicker growth rate of the trout and yield more nitrogen-rich waste for your plants.
Rainbow trout exhibit decent tolerance towards crowded conditions in water with good oxygen levels. However, they are vulnerable to sudden shifts in water quality, thus necessitating their rearing in a sizable tank to minimize temperature fluctuations. Moreover, polluted water can have adverse effects on rainbow trout, and if the plants fail to lower ammonia levels, an extra filtration system may be needed.
