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Stocking Aquatic Life
General Considerations
There is no “best” aquatic life selection for aquaponics. In many cases, is mostly depends upon what is available, what is legal for you to keep, and what will survive in your environment. Additional considerations such as special needs, developmental rates, food requirements and feeding habits, social behaviors and suitability to tank life , multi-cultural behaviors, reproductive needs and behaviors, and tolerance for variations in environment. There undoubtedly, still more considerations that will factor into your selection. However, this is a sound starting point.
Generally, any aquatic life should be as tolerant of environmental characteristics and variations as possible. Examples include: ammonia content, pH, oxygen content, water impurities, temperature, weather, food types, stocking densities. Your choice should ideally require minimal special needs considerations. It should minimize labor requirements. If it is selected for nutrition value or other harvesting requirements, it should rapidly and efficiently convert food to desire growth.
Aquatic life and plants selected for your Aquaponic systems should have needs that are similar or complimentary in nature. Optimal and acceptable temperature and pH ranges , for example, should be similar for aquatic life and plants. Plants depending upon highly acid pH will likely not survive or will marginally succeed in a pH leaning toward a higher pH. Similarly, a lightly stocked aquatic tank might produce enough waste to convert and sustain a grow bed of leafy lettuce. However, it might take a more heavily stocked tank and aquatic life with high waste production to support a grow bed of fruit vegetable such as tomatoes or cucumbers. Needs similarity or compliment are characteristics that increase chances of success.
Remember that environmental ranges are expressed as both optimal and acceptable ranges. While your system will survive and produce within acceptable ranges, truly successful results occur when optimal ranges are achieved and maintained.
Also remember your intended purpose for the aquatic life. Is it food an intended food source? Is it for ornamental purposes only? What, if any, are your harvest schedule and goals?
Be sure you have a good understanding of the differing environmental requirements and qualities of potential aquatic life when making your selection. Different species of fish, the most popular choice for aquatic life stocking, have different requirements and qualities, offering a wide range of considerations.
It is always best to consult with your local agriculture bureau to answer questions you may have regarding the best choices for your area.
Feeding Fish vs. Non-Feeding Fish Systems
One consideration often overlooked by beginning aquaponists is the choice between Feeding Fish and Non-Feeding Fish Systems. Obviously, all fish eat something. The differentiation is based on a trade off in Nitrates. In either event, a determination as to which type your system will be is a sound decision.
A Fed fish tank is characterized by fish eating food you add to the system. Because they are not intended to
eat the algae, the tank should not be exposed to sunlight. This keeps algae blooms to a minimum. The reduced algae translates to reduce diversion of nitrates, which increase the amount of fertilizer transferred o the grow beds. The result is great plant production.
Non-Fed fish tanks rely on the fish eating the algae that grow on the walls and bottom of the tank. Because algae need light exposure and consume nitrate in the water, this means a percentage of the nitrate initially intended for transport to the grow bed(s), is actually diverted to food for the fish. The result is a reduction in the amount of plants that can be fed.
Referring back to the stocking ratio rule of thumb for sizing the tank and grow bed, that ratio is anywhere from 1:1 to 1:3. In a non-fed fish system, the ratio is better targeted at 1:0.5 thru 1:15 up to 2:1, 2:2, or 2:3 tank to grow bed(s) volumes.
The trade-off in nitrate and in food production is an important consideration. He decision to create a non-feeding system has several advantages: 1) you don’t have to feed the fish; 2) upkeep and maintenance work a minimized, and; 3) the fish eat almost anything, including debris on the bottom of the tank. Conversely, disadvantages to this approach include: 1) lower plant (veggie) production, and; 2) increase monitor and control efforts to manage algae grow. The choice is yours.
Your choice of fed or non-fed system, also affects your fish or aquatic life selection. Stock must be vegetarian, at least in majority. Remember that non-vegetarian fish do eat something, and that something is likely your vegetarian fish or each other., so consider options carefully. How disappointing would it be, to find that two weeks after stocking tilapia and bass fingerlings in a multi-culture system, somehow, the bass consumed all of your tilapia?
A good suggestion combination for a non-fed system is a mix of feeder goldfish and tilapia. Both fish eat algae and other vegetation. They have highly compatible temperature, pH, and water quality tolerances. Best consideration yet, being vegetarian, they won’t eat each other.
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Food Source Fish
Tilapia
Tilapias are native to the tropics, but have been found to be highly adaptable to fish farming in the United States. Tilapia are cichlids. Cichlids are one of the largest groups of fish and include thousands of different species including Tilapia and many of the tropical fish found in a home aquarium. Tilapia are the main food producing cichlid of the cichlid group and have been farmed for many years in Asia. They are now becoming increasingly popular in other regions. The production of tilapia in aquaculture (fish farms) is roughly equal to the production of farmed salmon and trout. The advantages of using tilapia include fast growth, stocking density and their ability to eat plant-based food. They are sometimes called "aquatic chickens"!
Tilapia are recognized as the most popularly used fish (aquatic life) stocked in Aquaponics. Their species are an ideal selection for many reasons. The fish is edible, having an appealing mildly flavored, low fat, white flesh. They require little maintenance and care. They are easily bred, fast growing, omnivorous, and are highly resilient, withstanding significantly poor water conditions. Their highly adaptable and hardy nature make them an ideal selection regardless of system setup or size. They are easy to breed, fast growing, withstand very poor water conditions. They are less sensitive to fluctuations in temperature, pH, dissolved oxygen levels and build-up in waste than other species. Tilapia are quite at home in a tank environment. They easily adapt to living and quickly growing in high density stocking. They readily breed in a closed system environment.
Two important considerations apply to intentions of including tilapia in your system: 1) they do require warm water, and; 2) they are often considered an invasive species and prohibited in many jurisdictions.
Tilapia is suitable for warmer climates. Though they will survive and marginally produce at temperatures above 60 oF, their optimal temperature range is between 82 oF -86oF. They will survive outside that range, but their ability to flourish diminishes as temperature drops. Below 54 oF, they begin to lose resistance to disease and infections.
In colder regions, another selection might be a better choice, unless the system is established in a heated indoor space or somehow supplied with heated water. Remember that heating water and maintaining temperature is both difficult and costly.
Invasive species present significant detrimental risks to local ecologies. They often compete with an overtake indigenous species, overwhelming and eliminating them. Invasive species can disrupt the local food chain, destroying other species of animal and/or plant life. A great many unintended negative outcomes can occur when invasive species are introduced into a local environment.
The very aspects that make tilapia ideal for aquaponics present dangers to many local environments, should the fish be intentionally or un-intentionally released into the wild. Tilapia that make it into the wild are known to produce a hybrid species when they mate with other tilapia. These hybrids are often more destructive than their parents.
For these reasons, tilapia are often considered invasive species and are prohibited or regulated in many jurisdictions. North Carolina, for example, allows holding and breeding tilapia, in enclosed systems, only upon permitting by the N.C. Department of Agriculture, Wildlife Division. In Australia, their ability to overtake and dominate local waterways has made them illegal.
A with any potentially invasive species, if you are permitted to include them in your endeavor, you need to take some extra precautions with them. Special care must be taken to make ensure you do not accidentally release them into the wild.
They are highly adaptable and hardy variety of fish that can be used regardless of the setup or size of your system. If tilapia is not an option for you, then just about any common freshwater fish can be used in it's place. Other varieties commonly used in aquaponics systems are koi fish and crappie. It is always best to consult with your local agriculture bureau to answer questions you may have regarding the best choices for your area. Some growers even grow bass in their backyard systems. Tilapia are recommended because they are very hardy and add mass quickly, so your harvest of fresh fish will be optimized.
Large Mouth Bass
The highly popular game fish, largemouth bass, has a native range from the Great Lakes to south to the Gulf Coast, and from the Texas and parts of the south and mid-West to the Atlantic coast. Though not the best choice for beginners, this fish can be successfully grown in an aquaponic system.
The largemouth bass is less tolerant to unfavorable water and is more demanding in terms of care. It is intolerant to unfavorable water conditions, bright light, and poor nutrition. Water temperature and oxygen levels must also be controlled closely. Largemouth fingerlings and young, which primarily eat aquatic insects with fish, mollusks and crayfish in he wild, don’t readily feed on pellets. They must be trained to do so. Patience and long-term view are important to successful incorporation of largemouth bass, as they require 16-17 months to achieve table-ready size.
Water temperature and pH management are significant concerns with largemouth bass, Optimal temperature for growth is between 75°F and 86°F. Optimal growth pH is between 6.5 and 8.5. Optimal dissolved oxygen level is above 5.0 ppm. Brief exposures to lower temperatures, pH, and oxygen levels may survived.
The largemouth bass offers workable reproduction rates and behavior. A female largemouth bass may produce between 2,000 and 10,000 eggs in a spawning season with several males. The males participate in egg and fry survival, fanning the eggs to ensure oxygenation and defending both the nest and fry.
Because this fish is a voracious predator and are cannibalistic, suitability for aquaponic activities may be limited. Intensive culture system production is difficult. Typical options typically chosen are stocking operations in which fingerlings are sold to private and public organizations to stock lakes and ponds.
White Bass
Originating from the U.S. Midwest, White Base are popular in that they are offer a delicious plate. This fish is particularly popular when smoked. It averages 9 to 10 inches in length, and can possibly of attain 15 inches. The White Bass is carnivorous, making it a poor choice for non-fed fish systems. Though prolific in spawn, laying nearly one million eggs in a spawning season, the White Bass does not “rear” hatchlings, fry, or fingerlings. Instead the species leaves the spawning area after eggs are fertilized.
Crappies
Deliciously flavored and highly adaptable to closed aquaponic systems, the Crappie is another sound selection for your system. Because they are both carnivorous themselves and delicious to other fish, Crappie are a best excluded from non-fed systems and kept with similarly sized fish. Unlike the White Bass, Crappie males remain with fertilized eggs, protecting them through hatching. The most significant detractor to including Crappie is the long period of time (2 years) until they mature to breeding age and activity.
Bluegill/Bream
Sunfish
Yellow Perch
One of the most popular of North American pan fish, yellow perch have a habitat range from large section of Canada, including Nova Scotia, to South Carolina and Iowa and the Dakotas eastward to the Atlantic coast.
The yellow perch has a firm white flesh offering a highly versatile recipe component, and having a mild, sweet flavor. The yellow perch is low in fat, high in protein, and high in both calcium and Omega 3s. Because of it’s high value and the inability of commercial operations to meet high consumer demand, fillets can reach prices over $12 per pound.
Yellow perch prefer cool water. They grow to between 4 and 10 inches in length, with an average commercial production size of 8.5 inches occurring in approximately 2 years. Recent research and development by Hanping Wang, Director of the Ohio Aquaculture Research and Development Integration Program at the Ohio State University South Centers in Piketon, offers a sign cant improvement in mature times. Wang has practiced selective breeding techniques to produce yellow perch which reach commercial size in approximately 12 months. With this advancement, yellow perch become a very attractive aquaponics selection. Interestingly, the female yellow perch is both larger and faster than its male counterpart.
Because yellow perch spawn once a year, they are considered a seasonal fish and are only harvested a months of the year. To produce eggs, the fish must live in very cold water for several months, then when the water warms, they begin to lay in spawning cycles that achieve quantities of up to 30,000 eggs.
Catfish
Because catfish require careful monitor and control of ammonia and oxygen levels, they may not be best for beginning aquaponists.
Catfish continue to be important food source in the United States. Though overtaken in 2006 by Tilapia as the 5th most popular fish/seafood in the U.S., the National Fisheries Institue reports that as of 2010 catfish continued to be the 6th most popular . Of the just under average 16 pounds of fish/seafood consumed per person, just under 1 pound was catfish.
Many different species are suitable, with blue catfish being the most widely farmed in the United States and channel catfish highly popular as well. These rapidly growing fish do best in water temperatures closely centered around 80°F. They are very resistant to disease. Catfish are sensitive to both oxygen and ammonia levels, but will grow rapidly in a balanced symbiotic environment. Because they are bottom dwellers and leave upper tank strata to other warm water fish species, they are a good selection for multi-culture situations.
Because catfish are omnivores, they are better candidates for fed fish than for non-fed fish systems.
Trout
Very popular for its delicious taste, the rapidly growing trout, is an excellent choice for an aquaponic system. Trout popularity is on the rise, too. As of USDA reports from 2011, trout sales and consumption was increasing, with 7% increase reported in that year.
This fish grows rapidly in cooler (typically ranging between 40 oF and 65 oF), very clean water, making it ideal for cooler climates and over winter operations. Because they do eat other fish, trout are not cood candidates for non-fed fish systems. Instead, they do best in a fed fish system, where excellent food conversion rates result in rapid growth.
The fish is typically used for the season, then eaten.
Barramundi (A.K.A.: Barra, Silver Barramundi, Giant Perch, Palmer Perch)
Though difficult to acquire in the U.S., this fish is highly popular in Australia. This is a common fish in Australia, that can be found in both fresh and salt water varieties. It’s flesh is white and flaky, with a “crispy” taste, and larger fresh water varieties have high amount of body fat. Harvest yields are quite satisfactory.
Barramundi is characterized as a clean type of fish that grows well in warm water cultured systems. Because they are generally placid fish, they do well in large, higher density catchments with continuous water flow at temperatures above 20°C. It does prefer cooler water in warm climate, so it may be a good choice for aquaonpic operations in climate where winters are not cold enough for snow, but too cool for other warm water loving fish.
Barramundi are carnivores that prefer smaller fish, crustaceans, and aquatic insects. Because of this, they are not a good choice for non-fed fish systems. For the same reason, it is not wise to mix smaller Barramundi with larger sizes, as the smaller fish will likely become a food source in the system. Experienced auqaponists suggest a method in which small but more mature fish are purchased at the end of a growing season, so that larger fish are harvested from the system.
Jade Perch (Silver Perch)
Jade perch, also known as SilverBream, Bidyan, Black Bream, Grunter, and Murray Perch, is a warm water loving, Australian fish. It is an omnivore capable of achieving rapid growth on relatively inexpensive diets. High growth rates and very high Omega 3 oil content, differentiates the this perch from other species.
Despite it’s carnivorous ability as an omnivore with highly flexible dietary requirements, This perch is ideal in non-fed fish systems as they don’t eat other fish and highly docile.
Their willingnes for dietary flexibility is exhibited by their willingness to eat wide variety of vegetaion: pieces of vegetables (lettuce, cabbage, broccoli, Bak Choy, etc); pieces of fruits and fruit peels (kiwi fruit including peel, peaches, bananas including banana peel, etc); water snails; flower petals (various including rose, peach), and; bread and rice.
Murray Cod
Murray cod grow to enormous sizes in their native Australian habitats. Culture activities with this fish is in the early stages, so aquaponics experience is somewhat limited. This is a fast growing fish that is commonly used for a season, then harvested. Currently, Murray cod are typically grown in recirculation aquaculture systems, though they have also been grown in Aquaponics systems.
This fish does best in a fed-fish system, since they readily eat other fish. Despite their willingness to each other fish, the Murray cod can be a workable selection. However, it must be kept in high stocking densities that are well fed. If not they will exhibit cannibalistic behavior. The costs, efforts, and potential risk associated with high stocking densities increase the negatives associated with using this fish.
Pacu
Alligator
Domestic Cryfish
Australian Crayfish or also known as the Red Claw Crayfish (Cherax quadricarinatus)
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Ornamental Aquaponics Fish
Goldfish
Goldfish are a great, inexpensive, addition to an aquaponic system. Though they are not considered edible, they are sturdy fish capable of supporting your system, even under tough circumstances.
Goldfish are omnivores that will eat a variety of food including shrimp, earth worms, letuce and leafy vegetables, de-shelled peas, oranges, krill, daphnia, tubifex worms, elodea, duckwee, blood worms, other shrimp, algae, and commercial goldfish flakes. Because goldfish don’t eat other fish, and can readily thrive at high densities, it is a good choice for non-fed systems.
Feeder goldfish are an extremely inexpensive stock. They are readily available at many pet or aquarium stores for approximately $1.00 per 10. They readily coexist in mult-culture systems, including food production systems. They grow to fit your tank size (up to about 8 inches in length) , and they go dormant if wintered in outside tanks or ponds. The only requirement in that situation is an air hole placed in any formed ice.
Carp
Many species of carp are well suited to Aquaponics. The most common selection is known in Asian markets as Silver Carp. Though they have a fairly poor reputation in western cultures, has considerable popularity in Asia, is easy to acquire in the United States, and is the most widely culture fish in the world.
Common carp is an omnivore. It is naturally found in rivers, streams and lakes, feeding on anything that tastes good to them. Typical carp will eat aquatic plants, insects, crayfish, fish, freshwater mollusks, even nuts that fallen into the water. Because carp eat other fish, they are good for a non-feeding system.
One species of carp, the grass carp, was introduced into the United States in 1963 to control aquatic weeds. It was quickly recognized as a dangerous invasive species, because it will eat most any aquatic vegetation - having even been witnessed leaving the water to eat plants growing along the shore. These carp are now illegal in every state in the U.S. because of the potential damage they can inflict on plant species in waterways. In many Asian countries, many species are cultured but are being recognized as pest because of its reproductive capabilities and tough nature.
Koi
Koi is a species of carp. It does have an ornamental aspect, though, and is more widely recognized as “Koi”, rather than carp. It is very common in Asian communities. Often, schools of Koi are established in large ornamental ponds.
Though Koi is omnivorous, it does not eat other fish. This makes them a sound selection for non-0fed aquatic systems. It will however, eat small crustaceans, worms, insects, and other animal life dug from the mud in its habitat. Though naturally bottom feeders, they readily learn to surface feed. Because they will eat just about anything, water plants placed in their tanks are subject to consumption.
Various ornamental fish such as angelfish, guppies, tetras, swordfish, mollies
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A Word About Stocking Densities
Aquatic life stocking densities is a function of the amount of feed processed y your aquatic life and the amount of resultant waste that can be filtered by the system. “Naturally balanced” systems relying on bacteria, worms, and aquatic life as the filtration system will support far less fish per tank than will systems incorporating more sophisticated filtration systems. Systems using only grow media, bacteria, and worms for mechanical and biological filtration support smaller densities of aquatic life but also require less labor and equipment than do systems incorporating additional filtration systems. Higher densities of aquatic life can be achieved, but do require greater effort and expense.
Experts and experienced aquaponists report that a “naturally balanced” system typically supports 1 lb of grown out fish for 5 to 10 gallons of water. In this case, a tank of 100 gallons would support 10 to 20 table sized fish. Introducing additional waste removal techniques with additional components such as charcoal filtrations, UV systems, clarifying, mineralizing, and degassing tanks, may support up to 1 lb of fish per 1.5 to 3 gallons of tank water. This latter goal also requires more intense management, greater labor, and expense in both setup and maintenance. Disposal of waste may also be problematic from a regulatory perspective. These considerations are very often the driving factors moving home and hobby aquaponists to “naturally balanced” media base growing systems.
A Word About Grow Bed Densities
Grow bed densities are basically a function how much waste is available for conversion to plant nutrients, how well the grow bed bio-filter can convert the waste to nutrients, and sunlight and water availability. The more nutrients available, the greater the ability to increase plant density. Remember that plants require sufficient sunlight and water as well. Even at traditional spacing, aquaponic systems can readily produce 5 to 8 times the amount of plant harvest as an equivelant traditional gardening (don’t forget the significant water usage reduction as well!).
The Relationship between Stocking Densities and Grow Bed Densities
High densities of both stock and grow bed densities can be achieved by introducing additional resources together with nutrition, areation, and water quality improvement techniques. In the absence of such techniques, in a media based system, a good ratio to work with is approximately 1 cubic foot (7.5 gallons) of grow bed per 1 pound of grown out fish. If one adopts the 5-10 gallons of aquatic life tank volume per 1 pound of fish, then roughly 1 cubic ft of aquatic life tank will support 1 cubic ft of grow bed. This suggests a 1:1 ratio of volumes between the aquatic life tank and the grow bed. Though many home-based aquaponists adhere to this ratio, with a bit of patience and effort, 1:2 ratios and greater may be achieved.
Choosing the System for You
Your system design will be a function your goals, your resources, and abilities. Remember. Aquaponic can be extremely enjoyable and rewarding. It is, however, it is an investment in an ongoing effort. Consider your initial investment, as well as your ongoing investments.
If you are new to gardening, stock management, or aquaponics, smaller may be the better way to start.
Though aquaponics is not difficult to master, it is far better to minimize risk and effort until you are certain your interest is more than passing. Expanding your system, or developing larger systems is easy and straight forward.
Carefully consider your investments and commitment as well as the characteristics and costs associated with each design type before you begin.
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