The study was conducted to evaluate the potential replacement of fishmeal protein by gut weed (Enteromorpha sp.) protein and blanket weed (Cladophoraceae) protein in practical diets for the giant goramy (Osphronemus goramiJ fingerlings. A control diet containing fishmeal as main protein source was compared with 6 experimental diets in which fishmeal protein was replaced by increasing dietary levels of gut weed protein or blanket weed protein, namely 15 percent, 30 percent and 45 percent. All diets were fonnulated to be equivalent in crude protein (30 percent), lipid (7 percent) and gross energy (4 kcal/g). After 8 weeks of feeding trial, survival of experimental fish was not affected by the feeding treatments ranging from 80.0 to 82.2 percent. When comparing the control diet with the treatments of 15 percent, to 45 percent gut weed protein replacement, and the treatments of 15 percent and 30 percent protein blanket weed substitution, no significant differences (P0.05) were found for growth rates and feed efficiency. Particularly, fish group received the 15 percent gut weed protein substitution showed slightly higher growth and feed efeciency than those in the control treatment However, the giant goramy in the treatment of 45 percent protein blanket weed replacement showed significantly poorer growth and higher feed conversion ratio as compared to those in the control treatment and the treatment of 15 percent gut weed protein replacement (P0.05). These results indicated that fishmeal protein could be replaced by up to 30 percent blanket weed protein or 45 percent gut weed protein in practical diets for the giant goramy fingerlings.