The study was carried out to evaluate the use of fresh green weed (Cladophora sp.) as a feed for Tilapia (Oreochromic niloticus) fingerlings. Four feeding regimes were applied to triplicate tanks and fish was fed daily either commercial feed or green seaweed: (1) single commercial feed everyday as a  control treatment, (2) single green seaweed daily and 2 alternative feeding regimes where (3) 1 day commercial feed and 1 consecutive day green seaweed or and (4) 2 consecutive days green seaweed. Fish with initial weight of 3.5g were stocked in the 250-L plastic tanks at a rate of 20 fish per tank at salinity of 10 ppt. Fish were fed the respective diets to satiation twice a day. After 2 months of culture, survival of experimental fish was not affected by the feeding treatments (P>0.05) ranging from 93.3% to 96.7%. Growth performance of fish in the alternating feeding treatments, 1 day commercial feed and 1 consecutive day green seaweed was not significantly different from the control group fed solely commercial feed, whereas significantly reduced growth rate were observed in fish fed the green seaweed as a single diet. Proximate composition of fish carcass indicated that the highest crude lipid content in fish fed commercial feed while protein and ash contents have no influenced by the green seaweed replacement levels in the diet. Application of the combined feeding regimes, feed conversion ratio of commercial feed could be reduced from 18.3% to 30.8%. These results showed that fresh Cladophora sp. can be used as a feed to partially replace with commercial feed for rearing Tilapia. Moreover, using green seaweed as a feed could improve water quality in the rearing tanks.

Keywords: Cladophora sp., Oreochromis niloticus, growth, feed efficiency