Abstract
Yersiniosis or enteric redmouth (ERM) is responsible for significant mortalities among rainbow trout and other salmonids. Hence, its prevention and/or control has become a research hotspot. Antibiotics are effective for control; however, accumulating evidence indicates that unrestricted use of antibiotics harms fish, human beings, and the environment. Thus, finding safe, efficacious, cost-effective, and environmentally friendly substitutes is of great interest. Reports showed that dietary supplementation with functional additives with health-promoting and immunostimulatory functions could be a promising strategy. Herein, we provide an overview of the non-antibiotic feed-based strategies for combating ERM in rainbow trout without resorting to antibiotic usage. For this issue, the uses and application of some vitamins, probiotics, prebiotics, synbiotics, quorum quenching probiotic strains, algae, or organic acids, are included in the article. The roles of phytobiotics (herbal supplements), their phytochemicals, and the essential oils extracted from them will also be elucidated. Some emerging nano-based feed supplements are also discussed. Considering their advantages, literature declared that the dietary supplementation of these supplements could enhance the overall health condition, hemato-immunity, and disease resistance and conferred high protection of trout experimentally infected with yersiniosis. Given this perspective, this article presents the current situation and the latest knowledge on these supplements, emphasizing not only their roles to support immunity and decrease the effects of ERM, but also to minimize antibiotic usage in aquaculture. Limitations and future perspectives on their effectiveness and efficacy are also discussed. This review will help enhance aquaculture sustainability and improve the health and welfare of rainbow trout.