author(s)
Mohan Maloth, Varadaraju S, Jayaraj EG, Ganapathi Naik M, Shashidhar H Badami and Jaya Naik

abstract
Dissolved oxygen content is the most critical factor in intensive fish culture and it significantly affects the production of fish. Application of huge amount of fertilizers and fish feeds in heavily stocked fish ponds upsets the dynamics of dissolved oxygen. This becomes more pronounced in the early morning hours and on cloudy days resulting in severe depletion of dissolved oxygen of pond water. In addition to the problem of dissolved oxygen, toxic intermediates formed in the transformation of organic matter also inhibit growth of fish. These two factors which limit the production of fish in intensive culture, can be effectively controlled by the use of artificial aeration. Pond aeration systems were developed to sustain large quantities of fish and biomass materials. Aerator test results can assist in aerator design, aid aqua culturists in selecting aerators and provide a basis for estimating the amount of aeration required in specific situations. In the present study, four different types of aerators were designed and fabricated such as three tier perforated tray aerator, cascading wooden plank aerator, rotating wheel aerator and vertical perforated cylindrical aerator.