Use of Phytochemicals as Feed Supplements in Aquaculture: A Review on Their Effects on Growth, Immune Response, and Antioxidant Status of Finfish

Abstract

Aquaculture production is increasing day by day to meet the protein need of the global population. Various feed additives are used in aquaculture to enhance growth, stimulate immunity, prevent diseases, and strengthen the antioxidant status of fish. Phytochemicals attract attention among these feed additives. As phytochemicals are natural products, they are considered to be safe for fish, humans, and the environment. In this paper, we reviewed recent studies that utilize phytochemicals as feed additives in cultured fish species. In agreement with the available literature, we inferred that phytochemicals could be used in aquaculture. However, as some studies reported undesirable effects on growth, we believe that phytochemicals are more effective in immunostimulation and enhancing antioxidant status rather than growth-promoting. Possible reasons for growth retardation were emphasized. Although available evidence suggests that phytochemicals display beneficial effects, we discussed the possible use of phytochemical combinations to obtain even more desirable results. To conclude, we think that phytochemicals can exert synergistic effects, and this approach should be investigated in future studies.