Recirculating Aquaculture Systems (RAS)

Recirculating Aquaculture Systems (RAS)

Recirculating aquaculture systems (RAS) are designed to control the environmental facets of production by continually filtering, treating, and reusing water and thus increasing operational efficiency while reducing risks from pollution and pathogens. RAS have low direct land and water requirements and enable high stocking densities but do require large energy inputs and thus have high production costs, and waste disposal challenges. RAS technologies are typically beneficial when advantages in fish performance outweigh the increased costs. Grow-out operations in RAS are progressively focused on species with high market value.

Wageningen University & Research (WUR) uses recirculation aquaculture systems (RAS) in the Aquatic Research Facility of Carus (Carus-ARF). WUR is one the world leaders in this technology, based on more than 30 years’ experience.

Fish-system interactions

RAS combines a series of technologies aimed to keep water quality high. In combination with good hygiene, recirculating systems are rapidly becoming the first choice for much of the aquaculture sector. We believe that RAS integrate technological development, with insights into the complex relationships between water quality, ecosystem and host resilience (Ep Eding, Roel Maas, Aquaculture and Fisheries group).


Aquaponics combines the raising of fish or shellfish in RAS with cultivating plants in water, whereby nutrient-rich water from the aquaculture tanks is fed to hydroponically-grown plants. The water-reusing production of fish and crops is studied by prof Karel Keesman from Biometris.

Environmental technology

The Environmental Technology (ETE) group stood at the basis of the succesful development of RAS in the Netherlands. RAS require innovative environmental technologies and concepts based on processes from nature, such as denitrification, to recover and reuse essential components and maintain and create a viable environment.

Farm technology

RAS are mostly indoor systems combining a series of technologies that allow for intensive culturing of fish while minimising the use of natural resources, such as water and energy. The Farm Technology group (FTE) studies the potential of systems such as RAS for primary agricultural production processes.

Training the next generation

At Wageningen University, we train the next group of experts in aquaculture at annual International Fish Nutrition Workshops organised by the Aquaculture and Fisheries (AFI) group.