Recirculating aquaculture systems (RAS)

Last changed: 07 July 2021

RAS is the collective name for techniques where fish are grown in tanks or ponds on land. Water is purified by a variety of technical and biological purification steps.

Mechanical drum filters, carbon dioxide degassing, oxygenation and nitrification (conversion of toxic nitrogen products secreted by the fish) into biological filters and UV-sterilization of the water are the main purification steps. The fish density is usually high and the water flow through the system implies relatively high energy consumption in pumps and fans. However, production is high since growing conditions can be optimized according to the needs of a range of species.

There is a commercial interest in locating RAS close to cities, though research is scarce in terms of the opportunities and challenges related to such a development. Consequently, there is a need for cross-disciplinary collaborations.


Anders Kiessling, Professor, Department of Animal Nutrition and Management.