Aquaponics or fish farming. What it is, how it works and advantages

The  Aquaponics is a sustainable system of simultaneous production of plants and fish that combines traditional aquaculture (farming of aquatic animals) with  hydroponics  (growing plants without substrate but water with dissolved nutrients) in an environment symbiotic in plants they benefit from fish and vice versa. 


As we have said before, aquaponics has two fundamental parts: aquaculture , to raise aquatic animals, and hydroponics , to grow plants.

Aquatic waste from fish farming accumulates in the water through the use of closed recirculation systems implemented in most aquaculture systems. Waters rich in effluents and in high concentrations can be toxic to aquatic animals ; however, they are a source of essential nutrients for plant growth .


The aquaponic systems are usually grouped into different components or subsystems . Typical components include:

  • Breeding tank : where the fish grow and feed.
  • Solids Removal : a unit for removing uneaten food, detached biofilm, and fine sediment.
  • Bio-filter : the place where nitrification bacteria grow and convert ammonia into nitrates, so that they can be assimilated by plants.
  • Hydroponic subsystems : the part of the system where plants grow by absorbing nutrients from water.
  • Sump : the lowest point in the system where the water flows and is pumped back to the rearing tanks.



Nitrification is the aerobic conversion of ammonia to nitrates . It is one of the most important functions in an aquaponics system, as it reduces the toxicity of the water to the fish , and allows the resulting nitrate compounds to be removed by the plants and used for their nutrition . Fish constantly release ammonia into the water as a product of their metabolism , but most must be filtered as high concentrations of ammonia can kill fish. Aquaponics takes advantage of the ability of some bacteria to convert it into other nitrogen components. In this case we distinguish two types of bacteria:

  • Nitrosomonas : bacteria that convert ammonia to nitrites
  • Nitrobacteria : bacteria that convert nitrites to nitrates.

In the aquaponic system, the bacteria responsible for this process form a biofilm on all solid surfaces that are in constant contact with water . The submerged roots of vegetables have a large surface area, allowing many bacteria to accumulate on them. Taking care of these bacterial colonies is important to regulate the complete assimilation of nitrogen. Since the nitrification process acidifies the water, it is necessary to add non-sodium bases, such as potassium hydroxide or calcium hydroxide, to neutralize the pH of the water.


An aquaponic system is made up of two subsystems:

  • The cultivation of plants in hydroponics or hydroponic subsystem.
  • The fish farming in a related fishbowls , or subsystem aquaculture.

Hydroponic subsystems

The plants are grown in the same way as  in conventional hydroponic systems , with their roots immersed in nutrient-filled water. This allows them to filter out the ammonia that is toxic to aquatic animals and its metabolites. After the water has passed through the hydroponic subsystem, it is cleaned and oxygenated, and can return to the aquaculture vessels, forming a continuous cycle.

Most green leafy vegetables, such as lettuce , spinach, or chard ,  grow well in hydroponic subsystems. Other species of vegetables that grow well in an aquaponics system include: beans , radish, strawberries, onions, and aromatic herbs.

Freshwater fish are the most common aquatic animals raised using aquaponics, although crayfish and prawns can also be raised. In practice, tilapia is the most popular fish in projects for food consumption, although barramundi, silver perch, tandanus catfish ( siluriformes ) or jade perch are also used . For temperate climates, when there is no need to maintain water temperature, Lepomis macrochirus ( bluegill and catfish are good options for a home system. The Koi and goldfish (or goldfish) can also raise  if the fish are not for human consumption.


Aquaponic systems generally do not discharge or exchange water under normal operations, so they  recirculate and reuse water very effectively . The system relies on the relationship between animals and plants to maintain a stable aquatic environment that experiences a minimum of fluctuation in oxygen levels and nutrient environment. Water is added only to make up the loss due to absorption and transpiration of plants, by evaporation of surface water or removal of biomass as solid waste from the system. As a result, aquaponics uses approximately 2% of the water than a conventional farm.required to irrigate the same vegetable production. This allows aquaponic crop and fish production in areas where fertile soil or water is scarce.

The three main inputs to the system are: water, feed given to aquatic animals, and electricity to pump the water between the aquaculture subsystems and the hydroponics systems.


The advantages of aquaponic systems are:

  • Reuse of water , presenting an advantage for those areas where the availability of this is scarce.
  • Organic fertilization of plants with natural fish emulsion.
  • Solid waste disposal from intensive aquaculture.
  • The reduction of arable land necessary for the production of crops.
  • The general reduction of the footprint caused to the environment by the production of vegetables and animal husbandry.
  • The reduction of pathogens that frequently plague aquaculture production systems.

Some possible downsides of aquaponics are:

  • The initial cost of the installation.
  • The large number of ways the system can be configured tends to lead to equally varied results.
  • Some aquaponic facilities rely heavily on man-made energy , technological solutions, and environmental control to achieve optimal water and water temperatures and recirculation. Although if a system is designed with energy conservation in mind, using alternative energy and a reduced number of pumps leaving using gravity can be very energy efficient.

This is all. I hope you have found this topic of aquaponics crops interesting . Until next time gardeners!

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