The fast growth rates and survivability in adverse environments of the major flesh-water aquatic weeds auch as Salvinia molesta, Eichhornia crassipes, Hydrilla verticilata and Pistia stratiotes have caused tremendous problems in the water resources (limitation of light and oxygen supply) of various tropical countries where they have been introduced. Several attempts have been made to control these plants by biological, chemical and mechanical methods, but with limited success. Other methods to solve the problem of these plants by utilizing them either for waste water treatment or for energy production have been proposed in recent years.