β‐glucans are frequently included in the diet of healthy common carp Cyprinus carpio as a pre‐emptive measure for combatting disease. In order to study the effect this has on the relationship between the gut bacteria and host immune response, carp were maintained on either a β‐glucan free diet or feed containing 0.1% MacroGard®, a β‐1/3, 1/6‐glucan, for up to 7 weeks and analysis of innate immune gene expression and molecular...