A 42-day experiment was carried out to evaluate the fresh and dried gut weed (Enteromorpha sp.) as a direct alternative feeds for monosexNiletilapia (Oreochromis niloticus) comparing with commercial feed. Triplicate groups of fish with initial size of 3.04±0.48 g were stocked in 21 plastic tanks at a rate of 30 fish per tank. The water volume of each plastic tank was 80 liters. Fish were fed the respective diets to satiation twice a day. The results showed that the growth performance of O. niloticus in the alternating feeding treatments, 1 day commercial feed and 1 consecutive day fresh or dried gut weed (1CF_1FGW and 1CF_1DGW) were not significantly different from the control group fed solely commercial feed, whereas significantly reduced performance were observed in fish fed the fresh or dried gut weed as single diet. Carcass analysis documented the highest crude lipid content in fish fed commercial feed while protein content has no influenced by the gut weed replacement levels in the diet. Economic analysis suggested that the cost of the combined feeding regimes could be reduced with 41% without hampering the growth of tilapia. These results indicated that fresh and dried gut weed can be used as a feed to partially substitute commercial feed forNiletilapia O. niloticus juvenile.