In veterinary school we get extensive training in anatomy and physiology of many species, but we are never exposed to the incredible impact that gastrointestinal health applies to overall health, particularly in production animal species. The interconnectedness of the gut, immune system and microbiome is amazing. In this talk we will explore gut health, its impact on fish health and optimum production and how feed additives may impact the gut and other mucus membranes to improve health.