Transport stress experiments with Pelteobagrus fulvidraco and Piaractus mesopotamicus showed increased lysozyme and complement C3 contents [7,44], possibly because the transport stress impaired part of the immune capacity of the largemouth bass, combined with the deteriorated water quality accelerating pathogen proliferation, which exacerbated bacterial infection in the fish, thus activating the lysozyme and complement C3. This evidence concerns the gene LYZ and bacterial infectious disease.