Benthic samples were collected at around 11.00 a.m. fortnightly from all the experimental ponds using an Ekman dredge (bottomarea 15 cm × 15 cm). Collected samples with benthic invertebrates and bottom mud were washed and filtered properly with pond water. At first, samples were sieved through a 0.2 mm mesh-screennet for the separation of benthic invertebrates and large particles from mud and water. Then the benthic invertebrates remained on the screen net were collected using a fine forcep and kept into small plastic bottles containing 5% formalin for preservation. The smallplastic bottles were marked properly with a marker pen and taken to the laboratory for enumeration and taxonomic identification.