To identify the mechanism of duplicated c-type lysozymes in the innate immunity of goldfish for the prevention of bacterial disease, we isolated two c-type lysozyme (gfLyz-C1 and gfLyz-C2) cDNAs from goldfish and investigated their expression patterns in normal individuals and in specific tissues from the individuals challenged with pathogenic bacteria and immunostimulants. This evidence concerns the gene LYZ and bacterial infectious disease.