Aquaponics

Understanding Aquaponics

Fischhaltung, Pflanzenanbau und biologische Wasseraufbereitung als gemeinsam geplantes Produktionssystem.

Fish, plants and microorganisms in a production system

Aquaponics combines water-recirculating fish farming with soilless plant cultivation. Water and some of the nutrients produced in the fish area are used specifically for plant production.

The process can use water and nutrient flows multiple times, but is neither self-sufficient nor maintenance-free. Feed, energy, oxygen, supplementary water and professional management remain indispensable.

Basics

What is aquaponics?

The term aquaponics is a combination of aquaculture and hydroponics. Aquaculture involves keeping aquatic organisms, mostly fish. Hydroponics allows you to grow plants without grown soil. In an aquaponics system, both production areas are connected via water and nutrient flows.

Fish feed forms the most important nutrient input. Some of it is used by the fish for growth and metabolism. Dissolved excretions and solid residues end up in the system water. Mechanical and biological treatment stages ensure that these substances do not endanger fish health and that a usable proportion is available for the plants.

Aquaponics is therefore not a self-sustaining ecosystem, but rather a biological-technical production system. Fish, plants and microorganisms have different requirements for water quality, temperature, oxygen, pH and nutrient concentration. Planning and operation must reconcile these requirements with one another or control them specifically through separate cycles.

From fish feed to plant nutrition

How does aquaponics basically work?

The exact water path depends on the system architecture. However, the basic biological and technical tasks remain comparable.

Fish keeping and feeding

The fish consume food and release dissolved and solid substances into the water through their gills and excretions. Feed quantity, fish biomass and water quality determine the load on the system.

Treat solids

Feces, leftover food and other particles must be separated in a controlled manner. Depending on the system concept, they are removed, used separately or further biologically broken down in a mineralization stage.

Convert nitrogen biologically

In water, the reduced nitrogen is present as ammonium and ammonia, depending on the pH value and temperature. Nitrifying microorganisms oxidize it via nitrite to nitrate. To do this, they need sufficient oxygen and suitable settlement areas.

Supply plants with nutrients

The plants absorb nitrate and other dissolved nutrients through their roots. Since fish feed does not automatically provide all plant nutrients in the appropriate ratio, mineralization or targeted supplements may be necessary.

Move and aerate water

Pumps transport the water between the system areas. Reliable ventilation supplies fish, plant roots and microorganisms with oxygen. Technical failures must therefore be identified early and secured.

Return or transfer water

In coupled systems, the water flows back to the fish area. Other systems work with a controllable bypass flow, demand-controlled exchange or directional transmission without return.

Evaluate potential realistically

What aquaponics can do – and what it can’t

Potentials

  • Water can be used multiple times within the system.
  • Some of the fish-side nutrient flows support crop production.
  • Fish and plant production can be spatially linked.
  • Controlled environments enable targeted operational management.
  • The technology is suitable for education, research and demonstration systems.
  • Different system architectures allow different sizes and levels of automation.

Limits and requirements

  • Pumps and ventilation require a reliable energy supply.
  • Water parameters, fish health and plant development must be checked regularly.
  • Solids must not accumulate uncontrollably in basins, filters or root areas.
  • The nutrient composition of fish water does not always fully cover plant needs.
  • Fish, plants and microorganisms sometimes have different optimal environmental conditions.
  • Errors in sizing, feeding or oxygen supply can affect several areas of the system at the same time.

Organize water and material flows

Five system architectures in our overview

In the specialist literature there is no globally binding classification into exactly five aquaponics systems. For a clear technical orientation, Vida Vertical differentiates the systems according to the degree of their hydraulic coupling, the direction of water transfer and the number of independently controlled circuits.

Compare all five aquaponics systems directly

System 1

Fully coupled aquaponics system

Single loop · One circuit

Fish and plant areas share a continuous water cycle. After solids treatment, biofiltration and plant area, the water goes back to the fish.

Get to know the coupled system

System 2

Partially coupled aquaponics system

Bypass system · Adjustable bypass flow

The plant area remains part of the common circuit, but is supplied via an adjustable secondary stream. This allows flow and operating times to be adjusted to a limited extent.

Get to know a partially coupled system

System 3

Demand-controlled coupled aquaponics system

Own circulation · Controlled exchange

Fish and plant areas have their own circulation areas. Water is only transferred between areas at set times or depending on operational and measurement values.

Get to know demand-driven system

System 4

Completely decoupled one-way system

Double loop · Directional transfer

Water and dissolved nutrients are transferred from the fish cycle to the plant cycle. There is no direct return from the plant area to the fish.

Get to know a decoupled system

System 5

Multi-circuit aquaponics

Multi-Loop · Additional treatment

An additional treatment or mineralization circuit complements the fish and plant areas. This means that solids and nutrient flows can be prepared and dosed in a more targeted manner.

Get to know the multi-circuit system

deepen topics

Further aquaponics knowledge

Biofilters and bacterial conversion

How microorganisms convert nitrogen compounds and why oxygen, surface area and water quality are crucial.

To the specialist article

Fish rearing in aquaponics systems

Basics of fish species, keeping, feeding, oxygen supply and water quality.

To the specialist article

Correctly sizing aquaponics

Tank, biofilter, pump and plant area must be planned as a coherent system.

For planning assistance

Evaluate water consumption realistically

Which water losses actually occur and why the basis for comparison, climate and production are crucial.

To the specialist article

Aquaponics in agriculture

Classify areas, energy, water, labor and production goals for agricultural projects.

To the specialist article

Plan the pilot plant systematically

Derive a reliable decision from an experiment with clear goals, measured values and evaluation criteria.

For planning assistance

Technical basics

Selected sources

  1. Somerville, C. et al.: Small-scale aquaponic food production – Integrated fish and plant farming. FAO Fisheries and Aquaculture Technical Paper No. 589, 2014.
  2. Goddek, S. et al.: Navigating towards Decoupled Aquaponic Systems. Water, 2016.
  3. Goddek, S.; Keesman, K.J.: Improving nutrient and water use efficiencies in multi-loop aquaponics systems. Aquaculture International, 2020.
  4. Nishanth, D. et al.: Current technologies for nutrient recovery in aquaponic systems. Frontiers in Sustainable Food Systems, 2025.
  5. New Mexico State University: Decoupled Aquaponics – A Comparison to Single-loop Aquaponics.