The results of this research done in Guatemala bears on the growth of Tilapia (Oreochromis spp.) raised in floating cages for 168 days.

Six trials were made by grouping three diets with different pourcentages (0, 5 and 10 % ) of dried meal made of water hyacinth (Eichhornia crassipes (Mart.) Solms) with two density of fish (30 and 120 fish/m3).

The best growth rate (0,82 g/fish. day) was obtained in the cages of 120 fish/m3 with the diet including 5% of dried meal of water hyacinth. The second best growth rate (between 0,45 and 0,62 g/fish. day) was obtained from all the others cages receiving artificial feeding. The cages without artificial feeding got the lowest growth position with a gain of 0,22g/fish. day.

Generaly, in the experimental conditions met, it was posible to substitute 5 and 10 % of the control diet (0% of water hyacinth) prepared for Tilapia by dried meal of water hyacinth without causing prejudice to the growth of this species.