Importance of rotifers in aquaculture practices and its acceptability as a live food item for cultured organism has been recognised. In the Adyar Estuary, rotifers of the species Brachionus rubens and B. plicattilis were found in abundance. The biomass of rotifer in each of three stations together with data on salinity and suspended particulate matter were collected. A correlation between the biomass of rotifer and the total suspended particulate matter was drawn.

At Station 1, the suspended particle matter and salinity was high which ranged from 245 to 1086 rag/1 and from 8.8 %, S to 29.8 %„ S respectively. The salinity range and the amount of suspended particles were less in Stations 2 and 3. In general, very high and very low suspended particulate matter brought about a reduction in the biomass of rotifer.