From the constructive and functional point of view, a controlled aquaculture system can be assimilated with a classical water treatment system, functionally customized to the requirements of technology for intensive fish in confined spaces. A physicochemical process cheap, fast, secure which has the potential to replace the widespread technique of biologically removal of nitrogen compounds is based on the separation of nitrogen compounds from the water using zeolite. By using clinoptilolite, a zeolite with high affinity for nitrogen compounds, it was maintained in normal range the ammonia, nitrite and nitrate in a fish pound. The water recirculated in the controlled system was mechanically filtered and passed through the zeolite column. Clinoptilolite zeolite is an aluminosilicate from the microporous family solids which act as molecular sieve. The experiments were performed in the Laboratory of Fisheries and Aquaculture, Faculty of Animal Science, University of Agronomic Science and Veterinary Medicine of Bucharest. Advantages of this approach include: low dependence on temperature and absence of dependence on chemical toxins and bacterial predators, do not require a start-up period, the system can be turned off or on at will, fish is grown in much lower bacterial concentrations, reducing the possibility of disease or flavour loss.