This is likely to be mediated by the greater expression of the pro-inflammatory cytokine genes, tumor necrosis factor a (tnf-a), chemokine (C-X-C motif) ligand 8a (cxcl8a) and interferon gamma 1-1 (ifng1-1), and the elevated recruitment of neutrophils and macrophages to the site of infection, suggesting that the innate immune response in larval zebrafish is light-regulated. The gene discussed is TNF; the disease is infection.