HAMP and bacterial infectious disease: For example, long-term dietary supplementation with recombinant tilapia hepcidin 2-3 improved immune-related gene expression, reshaped the gut microbiota, and enhanced survival of grouper after Vibrio challenge [47], whereas oral administration of grass carp hepcidin, alone or in combination with chitosan, benefited growth, innate immune parameters, and resistance to bacterial infection in grass carp [43,48].