Aquaponics as a recirculation system

Aquaponics is the system in which conventional aquaculture combined with hydroponics in a symbiotic association. This system includes; hydroponics and aquaculture.

Aquaponics as a recirculation systemHydroponics

Hydroponic is a technique in which plants can grow in soilless medium while all the nutrients are applied to plants are dissolved in water. The liquid hydroponic system is a different technique such as nutrient film technique, non circulating water culture and floating rafts. All the essential nutrients are dissolved in water that plant uptake easily. Usually, these hydroponic fertilizers are derived from commercial fertilizers that are highly soluble in water such as, calcium nitrate. The major reason for hydroponic success is that one can apply very controlled conditions. 


Aquaculture is also known as aquafarming. It is the farming of aquatic plants and fish. Aquaculture is breeding, raising and harvesting fish basically it is farming in water. It is a responsible source of commercial products.


Aquaponics system is the combination of aquaponics and hydroponics. The reason behind this system is to get kitchen gardening because pure vegetables can be obtained from hydroponics and fish also from aquaculture. By aquaponics, we get both of that in one system. In this system, we can overcome the problems which may be arises from water quality. In recent years a lot of diseases appear from food just because of the poor quality of soil or water in the soil.

For this system, skillful or experienced person is better to overcome the problems arise in cleaning the water or handling vegetables.Moreover, fish feed contain 30% of crude protein that contains almost all off the essential nutrients required for plant growth. Plant use fish feces as a nutrient so no artificial fertilizers applied for plant growth.

A filter system may be added in this for the filtration of water. This filtration system removes fish feces which is present in water after plant use. These feces may be harmful for plants because it increases hypoxia condition by reducing oxygen amount from water. In a result death of aquatic animals may occur. So, aquaponics with the filtration system may be very effective.

At first, Aquaponics was performed about 1500 year ago in China. Later on, the development came in 1929 at the University of California. Controlled conditions are performed mostly for aquaponics such as greenhouses, which is used after world war 2. In 1970s the aquaculture researchers performed great work. They used a land-based tank for fish with recycled water continuously. But a major problem in aquaculture was an accumulation of nitrogen compounds in water.

They used soilless plants to overcome this drawback. And after that engineers introduced biofilters that did not rely on plants. It has been proven that this system improved water quality and also provides edible plants with a little more efforts and this property distinguishes it from other aquaculture or hydroponics systems.

Site selection

  • The surface should be level and stable
  • Safe from severe weather conditions
  • The system should designed in such a way that plants get sunlight throughout the day


Fish tank

The fish tank is very crucial in every Aquaponics system; fish require some specific conditions to survive. Some important aspects are shape, material and colour. But any type of fish tank can be used. The material should be durable. Plastic and fiberglass may convenient. Commonly low-density polyethene tanks used due to their high resistance characteristics.

Light color for tanks is advised because in light color fish can be easily seen. As white color reflects sunlight so, temperature does not rise too much. It could be beneficial to cover the tank because it prevents algal production, also control fish jumping out from the water and also control birds attack on fish.  


In aquaponics, biological filters are used. But on large scale biological filters do work slowly. For a large scale, mechanical filters may also be used. It is used to separate suspended waste and solids from the tank. It is very necessary to remove those solids because it may create hypoxic conditions due to anaerobic bacteria and there may be more chance of death of aquatic animals. It may also low down the flow of water. But in bio-filters, bacteria grow and convert ammonia into nitrates which are usable for plants such as nitrification bacteria.

Fish selection

Several cold-water and hot-water fish species have been used for aquaculture recirculation systems such as bass, arctic char, tilapia, perch, and trout. In North, America tilapia is been most commonly used. It is warm water species and hence grows better in the recirculation system. Tilapia is also resistant towards changing the environment of water such as temperature, ph, dissolved salts and oxygen. Moreover, it has a special type of meat that is beneficial for local as well as the wholesale market.

Water characteristics

Fish require good quality water that is present in the re circulation tank. Critical parameters for water quality are pH, dissolved oxygen, dissolved salts, carbon dioxide, nitrate, ammonia, chlorine and other characteristics. So, there is need to check water criteria after an interval.

Aquaponic plants

Basically, fish and plant selected for aquaponic should have similar characteristics towards some factors such as temperature and pH.  There should be some compromise between plants and fish closer they match more will be success. Commonly the combination of warm, freshwater, leafy crops and fish such as lettuce and herbs is best. In some cases, there could be some luck with plants such as tomatoes and peppers. Plants that will do best in the aquaponic system are;

  • Any leafy lettuce, Pak choi, Kale, Swiss chard, Arugula, Basil, Mint, Watercress, Chives, and Most common house plants
  • Plants have their higher nutritional demands and performed well in well established Aquaponics system; Tomatoes, Peppers, Cucumbers, Beans, Peas, Squash, Broccoli, Cauliflower, and cabbage.

In this system, the plant uses fish feces as a nutrient and fish uses plant residues.  There is no use of artificial fertilizer. It is a naturally organic system. There is no chance of weeding and hence no eradication problem occurs. In aquaponics, there is a low chance of damaging the plants by pests. Plant grows rapidly as compare in soil. In this system combination of fish and plants gives the phenomenon of polyculture that increases multiple products. In this system significant reduction in the use of water takes place. This system is helpful for the local economy as well as healthy food products. Fish manure water may also be used for irrigation purposes to improve plant growth. We can attain two products from one system. The hydroponic system became popular in many schools and colleges classes. commercially, it also became a source of income.


Aquaponic is a system to get benefits as vegetables and fish also. Fish are the rich source of essential micro nutrients and macro nutrients which are required for the proper growth of children. These days the main problem is food quality. A lot of diseases appear in humans just because of food insecurity. Leafy vegetables have the ability to uptake heavy metals in their edible parts that in swear condition can cause cancer like disease.

In aquaponic system food security can attain a high level in form of vegetables and fish also. It may also use as economically. Some countries that have some serious issue regarding soil or land cover they can secure their food by aquaponics as well as they can also import their products and can get high earnings.