What is recirculating aquaculture systems (RAS) RAS - a recirculating aquaculture system is a practically closed production circuit system, where more than 90% of the technological water is purified, saturated with oxygen and returned or reused continuously in production tanks. The produced waste products (solid waste, ammonium and CO2) are removed or converted into non-harming products by the technological system. By recirculating the water, the water and energy requirements are limited to a mi