Aquaponics FAQ

What is aquaponics?

Aquaponics is the combination of recirculation aquaculture and hydroponics. In aquaponics, you grow plants and fish together in one integrated system. The fish waste provides a food source for the growing plants and the plants provide a natural filter for the water the fish live in. This creates a sustainable ecosystem where both plants and fish can thrive. Aquaponics is the ideal answer to a fish farmers problem of disposing of nutrient rich water and a hydroponic growers need for nutrient rich water.  

Given the nature of recirculating aquaculture and hydroponics, the two technologies combined in aquaponics, there are 2 consistent factors in all aquaponic systems.  1.  Fish are raised in tanks.  2.  It is a soil-free growing system.

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Is aquaponics organic?

Aquaponics is a completely natural process which mimics all lakes, ponds, rivers and waterways on earth. The only input to an aquaponic system is fish food. The fish eat the food and excrete waste, which is converted (by beneficial bacteria) to a form that that plants can use. In consuming these nutrients, the plants help to purify the water. You can not use herbicides, pesticides or other harsh chemicals in an aquaponic system, making the fish and plants healthful and safe to eat.

This process could not be more organic but getting a USDA organic certification for a culture system that does not use soil is tricky. A couple of commercial growers in the US have had their plants certified as organic. The USDA has not finalized organic certification standards for fish yet.

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What are the benefits of growing Aquaponically?

The combination of aquaculture and hydroponics is quite new and the potential for using aquaponics to grow high quality food around the world is tremendous. Here are some of the many advantages of aquaponic food production:

  • Aquaponics utilizes the nutrient rich water from aquaculture that otherwise would have been a waste product or would need to be filtered in a costly manner.
  • Aquaponics eliminates the cost and time involved with mixing traditional hydroponic nutrients.
  • Aquaponics provides a truly organic, natural form of nutrients for the plants.
  • By eliminating the soil in vegetable production, you eliminate all soil borne disease.
  • Aquaponics uses a fraction of the water that traditional field production does because no water is wasted or consumed by weeds.
  • In aquaponics, plant spacing can be very intensive, allowing you to grow more plants in a given space.
  • With high stocking densities in the fish tank, plants will quickly grow and develop in an aquaponic system.
  • In aquaponics there cannot be any pesticides or herbicides used, making the end product healthier and safer.
  • If your climate permits or if you are growing in a greenhouse, you can grow crops in an aquaponic system year-round.

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What plants can I grow?

Early on in the research of recirculating aquaculture systems, experiments were done to determine the efficiency of aquatic plants in consuming the nutrients in aquaculture water, therefore helping to purify the water for the fish in the system. As research continued, terrestrial plants were tested and proven to be an effective means of water purification for aquaculture and this nutrient rich water a nearly ideal hydroponic solution for growing plants.

Lettuce, chives and other leafy crops were first considered for aquaponics but, more recently, commercial growers and researchers have had great success with tomatoes, cucumbers, peppers, melons, flowers and many other crops.

Visit Plants and Fish for Aquaponics for more information

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What fish can I raise?

Tilapia, a fresh water that is fast growing and has firm white meat when filleted, is most commonly raised in aquaponics because it is very hardy and can tolerate a wide variety of water quality conditions. Other fish, such as crappie, brim, bass, carp, goldfish and koi can all be raised in aquaponics. If you are considering home food production or commercial aquaponics, you should start by contacting the agency that oversees fish and waterways in your area to find out if there are any restrictions on what fish you can raise.

Visit Plants and Fish for Aquaponics for more information

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How many fish can I put in my fish tank?

It depends on the size of the tank and the type of filtration you have. In an aquarium-based system, a good rule of thumb is to stock the tank at 1" (of fish length) per gallon of water. In larger systems with proper filtration, commercial growers usually stock the tank to a maximum of 1/2 lb of fish/gallon of water.

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How many plants can I have with a certain number of fish?

The number of plants you can grow is directly related to:

  1. The number of fish
  2. The size of the fish
  3. The amount of fish food added daily

The scientists at the University of the Virgin Islands have determined that for each 60-100 grams of fish food added per day, you can support 1 sq. meter of plants in raft aquaponics.

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Can I make money doing this?

Maybe. Aquaponics, like any business, takes an adequate investment in equipment, proper design and excellent management and marketing skills. Plus, you need to be a skilled fish culturist and plant grower. With those qualifications, an aquaponic farm can be quite profitable.

Commercially, aquaponics is in its infancy but, as the technology develops and is refined, it has the potential to be a more efficient and space saving method of growing fish, vegetables and herbs. By incorporating aquaponics, hydroponic growers can eliminate the cost and labor involved in mixing a fertilizer solution and commercial aquaculturists may be able to drastically reduce the amount of filtration needed in recirculating fish culture. Although there is currently a limited number of commercial aquaponic operations, many people are expressing a strong interest in this intensive method of food production.

Visit Aquaponics Commercial Systems for more information.

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I found some old tanks, can I use them for the fish tank?

Your fish tanks and the materials used in your system should be food-grade plastics. This means that they won't leach chemicals into the water in the system. You should not use any tanks or containers that have had contents other than food or that aren't recommended for fish or plant culture.

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What do I feed the fish?

If your goal is optimum growth rates and food production, you should feed your fish a species-specific, commercially available fish food. There are many manufacturers of fish food. You can search for sources online or through local resources such as feed stores and ag suppliers. If you have a low-tech system and maximum production is not your goal, you can grow or make your own fish food. Duck week, water lettuce, worms and similar live feeds are often fed to tilapia.

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How does it work?

The key to a successful aquaponic system is the beneficial bacteria which convert the fish wastes into nutrients that the plant use.

More than 50% of the waste produced by fish is in the form of ammonia, secreted through the gills and in the urine. The remainder of the waste, excreted as fecal matter, undergoes a process called mineralization which occurs when Heterotrophic bacteria consume fish waste, decaying plant matter and uneaten food, converting all three to ammonia & other compounds. In sufficient quantities ammonia is toxic to plants and fish. Nitrifying bacteria, which naturally live in the soil, water and air, convert ammonia first to nitrite and then to nitrate which plants consume. In your aquaponic system the nitrifying bacteria will thrive in the gravel in the fish tanks and in the growing medium in the grow bed. The plants readily uptake the nitrate in the water and, in consuming it, help to keep the water quality safe for the fish.

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Do I need a greenhouse?

A greenhouse provides protection from enviromental factors such as heat, cold, wind, rain and insect intrusion. In most climates a greenhouse is required. A greenhouse can even be beneficial in the tropics to protect the crops from rain, wind and insects. The type of greenhouse and the enviromental control equipment varies widely depending on climate. There are aquaponic growers, however, that have hobby systems indoors, in a basement or garage. When indoors, they have to add artificial lighting for the plants.

Visit Greenhouses for more information

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Can I do this as a hobby or school project?

On a hobby scale, aquaponics is catching on quickly. A home aquarium, with ornamental or food fish, can be combined with a mini garden, growing herbs, vegetables or flowers. A hobby system can serve as a beautiful show piece or a food production system, depending on the size. Many backyard gardeners are setting up systems to grow hundreds of pounds of fish and all the fresh vegetables a family needs. If you are interested in hobby aquaponics or instructions on how to build a system for a science fair project, check out the book Desktop Aquaponics.

In educational applications, aquaponics is an excellent model of natures biological cycles. For educators, we have a comprehensive Aquaponics Curriculum Package, complete with an Educator's Guide, Student Manual, Transparencies, a CD-Rom and a subscription to the Aquaponics Journal.

The Aquaponics Journal is a bimonthly publication covering aquaponics. Each issue offers interesting, informative features on commercial, hobby, research, and educational applications of aquaponics.

For a thorough overview of aquaponics, we offer the recently released "Introduction to Aquaponics" on VHS Video and DVD.