Abstract: Due to the increasing demand for environment friendly shrimp aquaculture, herbs and herbal feed additives have received higher attention. A commercial Herbal Feed Additive (HFA) is a unique blend of selected herbs that act synergistically with each other to help in toning the immune system, protects hepatopancreas and activates several metabolic pathways that help in body weight gain. HFA was evaluated for its effects on the growth, survival, body compositions and the nonspecific immune responses of Penaeus semisulcatus. Three test diets were used vital prawn feed with 1 and 2% of the herbal feed additive HFA and the vital prawn feed without the additive (control). At the end of the study, there were no significant (P>0.05) differences among the three different diets in terms of shrimp mean weight, total weight, weight gain, Feed Conversion Ratio (FCR) and survival. The phenol oxidase activity was significantly (P<0.05) higher in the shrimp fed with 1% HFA than the shrimp fed with 2% HFA and the control. However, there was no significant (P<0.05) difference between 2% HFA and the control. The highest phagocytic activity was recorder in shrimp fed with 2% HFA, followed by 1% HFA, then the control. However, there was no significant difference in the PA (P>0.05) between the three different feeding regimes. Shrimp fed with 2% HFA contained significantly (P<0.05) lower crude protein and higher moisture than those fed with 1% HFA and the control. There was no significant (P>0.05) difference in the crude protein and moisture content of the shrimp fed with 1% HFA and the control. There was no significant (P>0.05) difference in the fat and the ash content of the shrimp fed with the three feeding regimes.