Failure to clean the pond bottom before stocking. After harvest, if the accumulated waste on the pond bottom was not properly removed, this will become a source of toxic gas after the pond is filled. The waste will absorb water and form a sludge covering the whole pond bottom. A slimy film is produced by dead plankton and it masses together and covers the pond bottom. At this stage if the water current is not strong enough, either because too little aeration is used or the water is too deep, it is not possible to remove this waste material.
Water is too deep.
During the first month, if the water is kept too deep, the current at the pond bottom will not be strong enough to remove the suspended solids. This leads to the accumulation of waste. It is recommended that the water depth during the first month should be no more than 1.2-1.3 metres. Incorrect aerator position. If the aerators are installed too far from the dike, it is not possible to remove the waste along the feeding area and pond slope, since the feeding area is approximately 3 metres from the dike.