D iatoms, besides the role of environmental condition indicator, also determine the water quality and are as interesting and intriguing phytoplanktons, as snowflakes. They took a primary role in various studies, in terms of oxygen, nutritional value and pollution indicator. The main primary producers in undisturbed and shaded zones of the streams are epilithic algae and play major roles in controlling energy flow of food webs in stream ecosystems [1,2]. However, the overgrowth of epilithic algae may deteriorate water quality [3]. The production and dynamics of an epilithic algal composition in stream ecosystems are also largely influenced by physical variables such as flow rate, light and water temperature [4,5]. The variation of epilithic algal biomass may indirectly affect the distribution of the Batlama stream. Water quality variables (electrical conductivity, pH, total dissolved solids, chemical oxygen demand, biochemical oxygen demand, and nutrients such as phosphorus and nitrogen from the surrounding lands) also play major roles in regulating the production rate and species com-Article History: