Plant essential oils as fish diet additives: benefits on fish health and stability in feed

Nutritional strategies focused on the use of phytochemicals as modulators of immunological and physiological responses, as well as antistress and antioxidant therapies and health promoters of the gastrointestinal tract have attracted increased interest in animal production. Over the past two decades, several studies have reported positive results of using plant essential oils (EOs) as dietary additive in several farm animal species. Recently, these nutritional alternatives have been evaluated and reported in fish production in order to enhance the resistance to diseases and prevent outbreaks, as well as to improve fish growth, animal welfare and feed utilization. However, despite the diverse and relevant biological activities reported, these phytochemicals are composed of often unstable and volatile molecules, which makes the chemical and physical characteristics of the EOs important aspects to be considered in fish nutrition research. This review summarizes the current knowledge regarding the use of plant EOs as fish dietary additives, focusing on their potential as modulators of the gut bacterial community and discussing some aspects regarding their stability in feeds.