The high temperature and pressure achieved during cooking extrusion has been shown to affect nutrient availability. To determine the effects of extrusion temperature on the efficacy of mannanoligosaccharide (Bio-Mos?) in channel catfish, 4 experimental diets were fed for 9 wks and then challenged with Edwardsiella ictaluri bacterium. Catfish (9.9 ± 0.4 g) were randomly assigned to the following treatments: Low-None (low temperature process without additive);High-None (high temperature process without additive);Low-Bio (low temperature process with 4 g/kg diet Bio-Mos?);High-Bio (high temperature process with 4 g/kg diet Bio-Mos?). Although specific growth rate and food conversion ratio were similar among treatments (P > 0.10), survival after E. ictaluri challenge was highest (P ?-laden feed resulted in survival numbers similar to diets without Bio-Mos?. Extruding catfish diets supplemented with Bio-Mos? at lower temperatures may provide another strategy to control enteric septicemia of catfish.