|Aquaculture is the fastest growing sector of animal agriculture. However, sustainable
expansion and intensification of aquaculture worldwide has been severely hampered by disease.
In the US catfish industry, the largest segment of US aquaculture, disease-based mortality levels
can reach nearly 60% over the course of a production cycle. Columnaris disease, caused by
Flavobacterium columnare, represents one of the largest sources of mortality in the industry.
Despite its importance, there are currently few effective weapons available to combat this
debilitating pathogen. Catfish producers are eager to gain protection against columnaris and
other diseases in a more natural and cost-effective manner, i.e. through diets supplemented to
provide for both mucosal health and performance. Here, we evaluated a Saccharomyces
cerevisiae fermentation product (Diamond V Original XPC™). The trial featured four levels of
inclusion which were added to a commercial 32% protein floating catfish ration. Following six
weeks of feeding, we observed heightened resistance to columnaris disease and saw significant
changes in the levels of immune effectors in the serum including lysozyme, complement, and
immunoglobulin. Our results stress the importance of understanding and prioritizing the
protective benefits of dietary ingredients for aquaculture species alongside more typical
consideration of a species’ minimal nutritional requirements.