All forms of planktons are not palatable. Some are even toxic and diatoms and some other forms of planktons contain low percentage of proteins. For harvesting planktons, some methods are used which include nets with arrangement to swing with the tides, low nets, a clarifier type of centrifuge, rotating type of screens and filtration of condenser water in large steam ships. Discovery of areas of high plankton populations, increase of plankton population by artificial means and the development of low cost equipment for harvesting plankton crop are needed.