An 60-day feeding experiment was conducted to investigate the effects of partial replacement of discarded filamentous green seaweed (Cladophora) with commercial feed on the growth performance and feed efficiency of spotted scat (Scatophagus argus). Triplicate groups of fish with initial body weight of 3.31 -3.39 g were reared in the 250 L plastic tanks at salinity of 5 g L^-1. Results showed that growth rate of fish in the alternate feeding regime, 1 day commercial feed and 1 consecutive day dried or fresh green seaweed were not significantly different (p>0,05) from the control group received single commercial feed. However, significant decrease in growth performance was observed in fish fed the fresh or dried green seaweed as solely diet. Application of the combined feeding regimes, the cost of commercial feed could be reduced up to 44.63% without hindering the growth of spotted scat as well as water quality was better than using solely commercial feed. Carcass analysis revealed that the lowest and highest crude lipid contents in fish fed commercial feed and green seaweed, respectively while protein and ash contents was not affected by the feeding treatments. These findings illustrated that the discarded fresh and dried Cladophora can be used as a feed to partially substitute commercial feed for S. argus culture.