The invention relates to a 
feed additive. The 
feed additive is prepared from a volatile oil mixture and a carrier, wherein the 
mass ratio of the volatile oil mixture to the carrier is 1 to (4-8), the volatile oil mixture is prepared by mixing turmeric volatile oil, fiveleaf 
gynostemma herb volatile oil and atractylodes 
rhizome volatile oil, and the carrier is beta-
cyclodextrin. The invention further relates to a preparation method and application of the 
feed additive in a feed for aquatic animals. Compared with the prior art, if the feed additive disclosed by the invention is applied to the feed for the aquatic animals, the 
antioxidant ability of the aquatic animals can be notably improved, the 
total antioxidant ability of serum and the activity of 
superoxide dismutase can be improved, the 
antioxidant ability of organisms can be improved, the 
oxidative damage of the organisms can be avoided, the 
immunity of the aquatic animals can be improved, the 
lysozyme vitality and complement 
vitality in the serum of the aquatic animals can be improved, the leucocyte 
phagocytic index in the serum can be increased, the health of the organisms can be improved, the growth rate and the 
survival rate of the aquatic animals can be increased, the growth is promoted, and a theoretical basis is laid for the development of the green raising of the aquatic animals.