Replacement of Fish Meal with De-hulled Soybean Meal in Diets on Growth of Subadult Hybrid Tilapia, Oreochromis niloticus×O. aureus

A feeding trial was conducted to evaluate the effect of replacing fish meal with de-hulled soybean meal (DSBM) in diets for subadult hybrid tilapia reared in a water re-circulating system. A randomized complete block design was used in the experiment. Tilapia with 155g initial mean body weight were randomly distributed 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), randomly assigned to 4 net pens in each quarter and fed to the tilapia. After 6 weeks' feeding period, no significant (P＞0.05) difference was found in percent weight gain, feed conversion ratio, and protein efficiency ratio among fish fed different experimental diets. Muscle composition was not influenced by the dietary treatments either. Feed utilization of subadult 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 might be able to utilize DSBM better than juveniles.