The photosynthetic benthic bacteria that break H2S at pond bottom have been widely used in aquaculture to maintain a favourable environment (Singh and Radhika 2001). These bacteria contain bacterio-chlorophyll that absorb light (blue to infrared spectrum, depending on type of bacterio chlorophyll) and perform photosynthesis under anaerobic conditions (Haung 2003). They are purple and green sulphur bacteria that grow at the anaerobic portion of the sediment-water interface. Photosynthetic purple non-sulphur bacteria can decompose organic matter, H2S, NO2 and harmful wastes of ponds. The green and purple sulphur bacteria split H2S to utilize the wavelength of light not absorbed by the overlying phytoplankton. The purple and green sulphur bacteria obtain reducing electrons from H2S at a lower energy cost than H2O splitting photoautotrophs and thus require lower light intensities for carrying out photosynthesis. The general equation of this reaction is as follows: