Diversity increased with age of the paddy field sites. In the 1975 site, bacillariophyta and chlorophyta were the most abundant phytoplankton algal group. This is because they are adapted to a wide range of physico – chemical parameters. Most of the phytoplankton encountered in the study area appeared to be normal inhabitants of natural lakes, ponds, streams and artificial impoundments in the tropics and subtropics (Nwankwo, 1998; Aneni and Hassan, 2003; Olaleye and Adedeji, 2005; Periyanayagi et al.,