To investigate the effects of photosynthetic bacteria as additives on water quality,microbial community structure and diversity,a photosynthetic purple non-sulfur bacteria,Rhodopseudamonas palustris,was isolated and used to remove nitrogen in the aquaculture water.The results of water quality showed that the levels of ammonia nitrogen,nitrite nitrogen,total inorganic nitrogen and total nitrogen in the treatment group were significantly lower (p<0.05) than the nitrogen levels of the controls in an extended range.