Immune response of channel catfish under different environmental conditions

Channel catfish were maintained under conditions of low (15.4 C) and fluctuating (15.4 to 26.9 C/24 hours) temperatures, low (126 mg/L NO3-N) and high (289 mg/L NO3-N) nitrate in recirculating systems, crowding (171 g body mass/L), and fasting. They were vaccinated with formalin-killed enteric red-mouth bacterium, and antibody titers were monitored weekly for 10 weeks. Only those fish maintained in low or fluctuating temperature environments had significant (P less than 0.01) immunosuppression. The other environmental conditions studies, which are commonly encountered in intensive fish culture operations, did not compromise the humoral immune response of channel catfish.