Bath immersion remains a practical route for immunizing against disease in channel catfish; however research efforts in this area have revealed variable results when activating mucosal Ab responses with different antigens. This is likely due to a number of factors including the individual species, age of the fish, preparation of the immunogens, and differences in the overall dosage and the duration of exposure to vaccines. The current study sought to evaluate the effect of water temperature on the in vivo mucosal adaptive immune response in channel catfish to a protein-hapten antigen, DNP-KLH. Fish were bath immersed at different water temperatures and periodically evaluated over an eighteen week period for the development of serum and mucosal IgM antibodies to DNP-KLH using an indirect enzyme-linked immunosorbent assay. None of the temperature groups produced a serum antibody response; however there were detectable DNP-KLH specific IgM antibodies in the mucus starting at week eight. The extent of the mucosal antibody response and duration differed between the treatments. Our results show that there are intrinsic differences in the capacity to generate in vivo mucosal Ab responses in the skin at different water temperatures and the implications of these findings to channel catfish farming will be discussed.