ABSTRACT The Mandau River area is a lowland area with the upstream part being a swamp with peat dome physiography. The Mandau River is influenced by the tides of the main river area, the Siak River. A research aims to know the type and abundance of zooplankton in the Mandau River, Sungai Mandau District, was conducted from July to August 2022. There were 3 stations namely in Muara Bungkal vill…