A successful aquaculture depends on the quality of soil, water, seed and feed. A good quality of soil, water, seed and feed always give a successful yield under skillful management practices. The ponds often accumulate with uneaten feed materials, excretions of culturing stocks, moulted shells, dead algae and surface run off organic matters carried by wind and water. When all these materials remain un-degraded or partly degraded in reduced oxygen condition, malodorous and toxic gases such as H2S and NH3 get developed. Toxic gases such as CH4, NO2 and others are also produced. These gases give rise to stress to the culturing stock resulting in loss of appetite, sluggishness, gasping for oxygen etc. and ultimately results to reduction in growth and mortality. The organic matter remains settled at the bottom, making a layer of scum, which on prolonged accumulation raises the pond bottom and makes a good harbor for the pathogens to proliferate various diseases. The finer organic particles remain suspended in water making turbid. These phenomenon exhibit high values of BOD and COD in the pond and very low level of dissolved oxygen.