List of the Best Fish for Aquaponics 2021 (US, UK, Canada & Australia)
Aquaponics is a cost-effective way of rearing most of your dietary requirements. It utilizes the biological properties of both plants and fish to balance water chemistry. Explored for its ingenuity as a means of achieving sustainability, it makes use of ecosystem services to solve many of the chemical problems and demands associated with both hydroponics and aquaculture.
As a practice, aquaponics has been around for thousands of years. As early as 1000 AD, the Aztecs reared plants on rafts that floated on a fish-filled lake! Strangely, we humans haven’t been able to fully hone in on this concept as modern-day aquaponics is still in its infancy, and definitely not as widely practiced as one would expect.
In a well-established aquaponic system, freshwater fish or crustaceans enrich water by providing a host of nitrogen-rich nutrients. This water is then accessed by the roots of edible plants, which contain nitrifying bacteria and the mechanisms by which nitrogenous compounds are converted to plant food. Stripped of potentially harmful nutrient concentrations, the same water can then be re-used in the fish rearing tank. In this way, fish waste is used as fertilizer for plants, and plants are used to “cleanse” the recirculated water.
General Considerations in Fish Selection
While it makes more economic sense to grow edible leafy plants (e.g. basil, cabbage, lettuce), the fish in an aquaponic system can be both edible or inedible. You can even opt to make use of ornamental fish if interested in the decorative possibilities of aquaponics. Essentially, your choice of fish species should depend on their ability to withstand crowded tank conditions and on their tolerance for varying water parameters.
Moreover, your selection must be paired appropriately with the ambient conditions in your area. Temperature should be a significant factor. For example – if you live in a northern temperate region, it may be best to opt for coldwater fish. Choosing warmwater fish may ultimately cost you more in maintenance costs as temperature regulation would be required for most of the year.
The size of your rearing tank, fish growth rates, the maximum size of fish species, and their breeding tendencies will have to be considered as well. An exceedingly high fish density can quickly throw off the balance of an aquaponic system. Oversized fish may also be susceptible to stress-related diseases in a crowded tank. Lastly, fish diet and oxygen requirements must be taken into account. These will undoubtedly influence your system maintenance costs in the long run.
Below are some of the most popularly reared fish in aquaponic systems. Their hardiness and resistance to many diseases make them great candidates for growth in recirculated water. Do try to select fish that are native to your area and check your state’s invasive species list when designing your system.
List of the Best Fish for Aquaponics
1) Tilapia (Cichlidae spp.)
Tilapia are ideal candidates for aquaponic systems because they are able to tolerate a wide range of conditions. This hardy fish is known for being resistant to pathogens, crowded situations, and low oxygen concentrations that would stress many other types of fish. Most tilapia species can thrive on an omnivorous diet of both plant-based and live foods. They are warmwater fish and are most comfortable when reared in tanks with temperatures maintained at 27 – 30˚C (82 – 86˚F), although they can withstand dips of up to 12.8˚C (55˚F).
Notorious for their rapid growth rate and propensity to breed, tilapia can be either highly beneficial or troublesome in a tank. Though they are considered beginner-friendly fish, they must be harvested quite frequently to counteract reproduction rates. If conditions are appropriate, you can expect to harvest tilapia from your system every six months. Fortunately, they are highly edible fish and can be incredibly delicious when prepared correctly.
2) Catfish (Clariidae, Ictaluridae, and Plotosidae spp.)
Several catfish species are known for being beginner-friendly options for aquaponic systems. These include eel-tailed catfish (Tandanus tandanus), channel catfish (Ictalurus punctatus), brown bullhead catfish (Ameiurus nebulosus), and African catfish (Clarias gariepinus). They are remarkably hardy species that can tolerate low oxygen conditions and wide fluctuations of temperature and water alkalinity.
Catfish are often stocked at higher densities than other fish because their bottom-feeding habits make them tolerant to high ammonia concentrations. “Personal space” doesn’t quite apply to them as they are non-territorial and are comfortable hovering right next to one another! Due to their behavior, it would be best to rear them in wider rather than taller tanks. They prefer to scavenge close to the bottom of a tank and will appreciate the horizontal space.
If concerned about the electrical supply in your area, it is likely that catfish would be your best choice. Mechanical filtration need not be consistent for catfish, particularly if they are reared in lower concentrations. The only thing you may need to watch out for is temperature. Most catfish are warmwater species and have preferences similar to that of tilapia (i.e. ranging between 24 – 30˚C or 75 – 85˚F).
3) Barramundi (Lates calcarifer)
A saltwater fish in an aquaponic system? Also known as Asian sea bass, barramundi is a catadromous species that lives most of its life in freshwater. It ventures into bodies of saltwater just to spawn. Unlike tilapia or catfish, this species is quite sensitive to water conditions and may require the expertise of someone with previous experience in aquaponics.
Though challenging, rearing barramundi can be extremely rewarding. This species is known for its fast growth rate and highly nutritious meat. Given proper conditions, barramundi can reach harvest size in little more than five months! To ensure that they grow at this rate, the stocking density of your tank must be calculated carefully. Each fish will require up to 20 gallons of water volume, particularly if you wish to rear them to their maximum size (0.6 – 1.2 meters).
Barramundi will thrive best in warm water temperatures ranging from 23 – 30˚C (74 – 86˚F). If located in an area experiencing cooler temperatures, you may need to equip your tank with reliable water heaters. You may also opt to grow barramundi during the warmer spring or summer months, and harvest them as soon as they grow to around half a kilo. To ensure that they quickly reach this size, feed this predatory fish with high-protein sources, such as worms, beef hearts, small fish, and shrimp.
4) Koi (Cyprinus rubrofuscus)
If you’re more interested in rearing fish for ornamental purposes, you can definitely choose to rear koi in an aquaponics system. These prized fish will require a large tank (i.e. 200+ gallons per individual) with ample depth. Compared to many non-ornamental aquaculture species, they may also need additional filtration and higher dissolved oxygen levels.
Koi are highly adaptable fish. Given proper conditions, they are fairly resistant to pests and diseases. For this reason, they can quickly adjust to being reared in close quarters. If you are located in a temperate area, this coldwater species may be just right for you! They can survive in winter temperatures outdoors, but do keep in mind that their tank temperatures should be maintained at above 18˚C for optimal growth.
Because they can live for up to 35 years in captivity, koi tend to be worth the investment. However, they will require more food and produce more waste as they grow larger. This requires serious consideration as an inappropriately sized tank and lack of filtration can do more harm to your system. Of course, if you can pull off rearing large koi in an aquaponics set-up, that would surely be a sight to behold!
5) Goldfish (Carassius auratus)
If you’d like to achieve an ornamental appeal for your aquaponics system, but are unable to satisfy the needs of koi, consider rearing goldfish. With dozens of varieties to choose from, you can fill your average-sized aquaponics tank with more than a dozen varieties of goldfish. This would certainly make your system endlessly eye-catching, without emptying your pockets the way a koi tank would!
On average, goldfish grow to just 6 inches in large tanks. They can grow much larger in the wild or in outdoor ponds, but will remain quite small in a standard aquaponic system unit. They are undemanding as a species and can thrive even in slightly polluted conditions. Tolerant of fluctuations in pH, goldfish are hardy fish that can be relied upon to produce beneficial nutrients for your plants. To achieve a balance, the number of goldfish in your tank should depend on the filtration capacity of your plant tank.
Goldfish are coldwater fish that will thrive in cooler temperate zones. If your tank is not small enough to transfer indoors for the winter, a regular heater will suffice provided it can prevent water temperatures from dipping to below 15˚C (59˚F). Make sure to choose hardier goldfish varieties, such as those that are slim-bodied (e.g. comet, common, wakin, shubunkin, watonai), instead of fancier types if your tank must be left outdoors all-year-round.
6) Perch (Percidae & Terapontidae spp.)
Several species of perch can easily be reared in aquaponic systems. These include yellow perch (Perca flavescens), silver perch (Bidyanus bidyanus), and jade perch (Scortum barcoo). One of the main advantages to rearing perch in a tank is their inability to breed in captivity (with the exception of those in tightly controlled hatchery set-ups). Although perch do have a rapid growth rate, you won’t have to worry about them eventually overcrowding your tank. By harvesting sparingly or in a moderate manner, you can ensure that a sufficient amount of nutritious waste is provided for your plants.
Due to their schooling nature, perch can be reared at fairly high densities. They can also tolerate relatively high ammonia levels and marked fluctuations in pH. Depending on the species, perch can be herbivorous or omnivorous. In the wild, they are generally quite low on the food chain. Most species can be sustained with a diet of fish feeds. Given proper food, they develop highly nutritious meat that is rich in omega fatty acids.
Perch can grow to their full size within just a year of culture. The aforementioned species rarely exceed a length of 10 – 15 inches when raised in captivity. They can withstand temperatures ranging from 17 – 28˚C (cooler than the temperature requirements of tilapia). If you can locate your aquaponics system in a greenhouse, perch would be an ideal candidate for your fish-rearing 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).
Rainbow trout can be fed with a wide assortment of food choices. When grown in captivity, they can survive on an artificial diet of grain-based feeds. However, those reared in an aquaponic unit would best benefit from a high-protein food source as this would help them grow at a faster rate and generate more nitrogen-rich waste for your plants.
Rainbow trout are fairly crowd-tolerant in well-oxygenated water. Unfortunately, they are quite susceptible to marked fluctuations in water quality and must be reared in a large tank to reduce rapid changes in temperature. Rainbow trout are also sensitive to polluted water and may require an additional filtration unit if your plants are unable to significantly reduce ammonia concentrations.
8) Bluegill (Lepomis macrochirus)
Bluegill are an ideal species to raise in an aquaponic system because they can tolerate a wide variety of conditions. These hardy fish are a popular choice for beginners due to their inexpensive care requirements. There are technically two bluegill subspecies that vary in size but have similar preferences. Interestingly, they are most suitably grown alongside raspberries, grapes, and spinach!
Bluegill can be kept in reasonably sized tanks; a 55-gallon one is suitable for rearing five individuals. They do grow to be quite long, so your tank size has to be adjusted according to your harvest preferences. These fish can live for up to 6 years, but typically reach harvest size after just a year if conditions are optimal. Maintain temperatures at 18 – 26˚C and a pH level above 6 to ensure that your bluegills metabolize at a normal rate.
9) Largemouth bass (Micropterus salmoides)
Even fish enthusiasts who pride themselves on maintaining consistently clean water systems may meet some challenges while rearing this formidable species. Largemouth bass are highly sensitive to water pollution and high levels of potassium. In the wild, they thrive best in crystal clear lake waters where they can easily catch sight of their prey! Fortunately, they aren’t as sensitive to fluctuations in temperature and can grow normally under a wide range (12.8 – 29˚C/55 – 85˚F).
Largemouth bass are ideal candidates for aquaponic systems because they are able to tolerate low oxygen conditions and pH levels. They are fairly resistant to high nitrite levels as well. If you’re looking for a fish that you can rear for an extended period of time, without having to harvest intermittently, you should definitely consider this species. This doesn’t mean that you can’t give your fish a try after just a year of growth, however, as fingerlings can grow to a decent size within this time frame.
In terms of feeding requirements, largemouth bass are surprisingly easy to satisfy because they don’t require high protein diets and can be trained to accept fish feeds. It can also be exciting to watch them eat, as they tend to feed right at the water’s surface. Food sinking to the bottom of a tank is a telltale sign that your fish have been given too much to eat. Care for your bass well and be rewarded with great-tasting meat at each harvest!