Plankton is a microscopic organism floating freely in water. They are of two types namely phytoplankton or plant particles and zoo-plankton or animal particles. If the color of the water in the pond is green or greenish, it should be understood that there is phytoplankton in the water. Phytoplankton is also called unicellular algae. Examples of some phytoplankton are Chlorella , Annabena , Microcystis etc. Some of the notable zoo-plankton are Daphnia , Copipad , Rotifer . If the color of the water is brownish green , reddish-green or yellowish green, then it should be understood that phytoplankton as well as zoo-plankton content in the pond is also good. In order to produce plankton in the pond, it is necessary to use regular fertilizer by providing adequate ventilation. Both organic and inorganic fertilizers can be used as fertilizers.