Surface water bodies, e.g. inland freshwater lakes, can suffer from excessive inputs of pollutants and nutrients which damage their natural buffering and self-cleaning capacity in different ways. Bio-manipulation techniques can be used for rehabilitation of damaged surface water systems. Here we give one example of scientists that work to convert muddy fish pond into clear water body with better water quality a project that concerns biomanipulation. It is a special treatment of aquatic ecosystems where the natural relationships between main components of a lake or a reservoir are being used for rehabilitation. It means we try to modify food webs, mainly between plankton and fish or in the fish community itself. This means also that we influence the availability of phosphorus, the key nutrient for planktonic algae.