Duration Of Fasting And Its Effect On Stress-Induced Aeromonas hydrophila  Bacteremia In Channel Catfish     Kenneth E Nusbaum1, Edward E Morrison2, and John M Grizzle3   1Department of Pathobiology, 2Department of Anatomy, Physiology, and Pharmacology, College of Veterinary Medicine, and 3Department of Fisheries and Allied Aquacultures, College of Agriculture, Auburn University, AL     During a water-borne challenge of channel catfish with Edwardsiella ictaluri, a bacteremia of primarily Aeromonas hydrophila was detected as early as 3 hours post challenge.  Aeromonas hydrophila bacteremia could also be induced simply stressing fish  by drawing several blood samples over an 8 hour period.  Although A. hydrophila were readily isolated from the head kidney, the suggestion was made that the actual source of the A. hdrophila may have been from the gut.  This work attempts to define the contribution of gut borne bacteria to stress-induced bacteremias of channel catfish. Channel catfish from two egg masses were hatched and reared indoors on de- chlorinated city water.  Four groups of ten month old fish (n=10) were held at 20 C in static aerated water in 38 l tanks.  Food was withheld from fish for 1, 2 or 3 days.  Fish were then subject to handling stress (netting and blood sampling) 3 times over 5 hours.  Half the fish were then tranquilized at 8 hours of stress and blood samples drawn for quantitative culture on Rimler-Shotts agar.  Fish were then anesthetized and dissected.  Distribution of gut contents was noted and cultured quantitatively on Rimler-Shotts.  Samples of gut were harvested for microscopy to determine if bacteria were traversing the gut wall.   Progress of this investigation will be reported