A feeding trial was conducted to evaluate the effect of replacing fish meal with de-hulled soybean meal in diets for pre-marketing size hybrid tilapia reared in a water re-circulating system. Hybrid tilapia with 155 g initial mean body weight were randomly assigned to 16 net pens that were placed in four quarters of a water re-circulating system. Four isonitrogenic and isocaloric diets were formulated to contain 0-20% fish meal (or 57-29% dehulled soybean meal) and fed to hybrid tilapia for 8 weeks. A randomized complete block design was used in the experiment. After 8 weeks feeding period, no significant difference (P>0.05) was found in percent weight gain (WG), feed conversion ratio (FCR), and protein efficiency ratio (PER) among fish fed different experimental diets. Muscle composition was not (P>0.05) influenced by the dietary treatments either. Feed utilization of large size fish in this trial, however, is somewhat better than the juvenile fish fed similar diets and reared in aquaria in a previous study. Large size hybrid tilapia may utilize de-hulled soybean meal better than juvenile fish.