Of note, a diet effect (FO diet vs. VO diet) on the mucin gene expression was not found for Muc2, Muc2-like and Muc13 in either control fish or infected fish, but the expression level of the I-Muc in fish not exposed to parasite infection was significantly lower in fish fed the VO diet than in fish fed the FO diet. The gene discussed is MUC13; the disease is infection.