Aquaculture in fresh water as well as salt water is highly dependent on the location. It is only possible to produce the types of fish which are adapted to the natural water quality and temperature at the location. Limiting factors are, as a rule, water quantity, oxygen content and water temperature. When production is accomplished using recirculating systems the quantity of water available can be increased significantly by treatment of the water. Even species which prefer warm water such as pike, catfish, tilapia, eels and perch can be farmed throughout the entire year at constant temperatures. This not only increases the productivity; it also optimizes the use of production resources, such as food, because the metabolisms of the fish can be stabilized under optimum conditions. Our Recirculating Aquaculture System (RAS) design includes: Drumfilters for mechanical filtration Trickling filter, moving bed filter or fluidized bed filters for biological cleaning in recirculation plants Denitrification units Degassing units for hatcheries and recirculation plants UV and ozone water disinfection