In the present work an attempt has been made to evaluate the bottom biota through species diversity in a polluted pond (Lilashah Pokhra) at Duraundha Block, Siwan District. The dominant species were Chironomas and Vivipera bengalensis. The physico-chemical parameters of the pond water (such as pH, DO , Free CO , Chloride, Alkalinity, Hydrochloride, Carbonate and Bicarbonate, Nitrate, Silicate and Iron 2 2 etc.) have also been studied. The details have been discussed in this paper.