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 (P0.05) difference in the fat and the ash content of the shrimp fed
with the three feeding regimes.