Eichornia crassipes is one of the most dangerous aquatic weeds for Lake Tana .To reduce its invasion biological, chemical and physical control methods can be used. Use of natural enemies of the weed to discourage its propagation is one of the best recommended options by scientific society. Among them, there are more fungi naturally a pathogen for water hyacinth and other plants. To use those patogenes to manage water hyacinth infestation in Lake Tana infected plant material by fungi were collected from three weredas (Amba Gyorgese, Dabat and Debarke) around Gondar since Novmber 2015. The collection was done from infected Faba bean leaves and roots. All isolated fungus was attempted to infect the collected healthy water hyacinth in laboratory and green house. Some of the isolated were show high moderate disease severity on the healthy water hyacinth. Disease severity scale was recorded .By following those experiments to show its efficiency, the effective pathogens on laboratory and green house were released to 16 m2 open ponds .In this study, we have recorded scientific data that shows the fungi were high potential to attack healthy water hyacinth at above 26 oc and at less than 25 % humidity.Finally, before directly release the fungi on Lake Tana its impacts were studied for a year by taking some aquatic plants and fish from the Lake. Fortunately, those fungi have not impact on some aquatic plant like Echinochloa and Cyperus papyrus grass, water quality and fish.