I. Introduction Aerators are essential in semi-intensive and intensive aquaculture to maintain an environment congenial to the physiological requirements of the cultured organisms. In an intensive aquaculture, full demand ofoxygen supply of the cultured species cannot be met through natural aeration process only. Therefore, artificial aeration through acrators becomes essential. Aerators increase the interfacial area between air water, thus enhancing the and oxygen transfer and simultaneously provide water circulation which prevents the stratification n the water body (Boyd and Martinson, 1984). Various types of aerators have been developed over the years to maintain desired of dissolved oxygen (DO) concentration in the pond level water in an effort to improve the energy efficiency ofthe oxygen mass transfer process. vertical pump sprayers oves), Propeller Aspirator Pumps (PAP, Paddle wheels (Pw), and diffused-air systems are probably the most widely used aeraton in the field of aquaculture Boyd, 199s). wheel acrators were found to be the most efficient aerator in terms of Paddle aeration efficiency and circulation (Rappaport et al., 1976 and Boyd and Ahmad, 1987) Recently Singh (2010) designed and developed circular stepped cascade (Csoaerator. CSC aerator consists of six circular steps arranged one above the other with their radii deer in a uniform manner from bottom to top with qual height of each step. At the central portion of the CSC, a propeller pump is attached for delivery of water at the top of the step. Adetailed design specification of cso aerator is available in Singh (2010. Kumar et al. (2013) developed POscaerator by providing partial banriers at the periphery of each of the eircular steps of CSC aerator to increase the time of exposure of falling water. These aerators, ie cso and Pcsc were found to be very cheap and hardy because of their simple design. The SOTR for both CSC and PCsc aerators were found to be very low in comparison to paddle wheel aerators. However, their lower capital investment and lesser wear and tear in contrast to