Besides the large area needed, the problem within this system is that the process is completely dependent on the
availability of sunlight (Azim and Asaeda, 2005). On cloudy days or on days with insufficient sunlight, the maximum nitrogen uptake rate will not be reached. Another problem is the laborious task to harvest the periphyton. One can conclude that application of the periphyton treatment technique in the intensive aquaculture sector is not feasible. Nevertheless, the technique of using this natural feed may be significant, particularly in smaller, extensive-level aquaculture systems in developing countries. The addition of the ‘periphyton loop’ in aquaculture ponds can be accomplished by adding static substrates to the pond (Azim et al., 2005), such as poles horizontally planted in the ponds. Substrates used are bamboo, hizol and kanchi (Azim et al., 2002, 2003c). Since periphyton can be easily cultured in modified fishponds and demands little management, the benefits may be substantial.