TWENTY-THIRD ANNUAL EASTERN FISH HEALTH WORKSHOP JOHN CARVER INN, PLYMOUTH, MA 30 MARCH - 2 APRIL, 1998 Citrobacteriosis Associated With Mortality In Aquaria-Reared Angelfish Scott D. Fitzgerald Animal Health Diagnostic Laboratory & Dept. of Pathology, College of Veterinary Medicine, Michigan State University, PO Box 30076, Lansing, MI 48909-7576 A tropical fish farm lost 2,000 out of 5,000 young Angelfish (Pterophyllum sp.) over a 7 day period. These fish exhibited listlessness, inappetence, pale stringy feces, and rapid mortality in the young. The breeding adults had much lower mortality but had decreased spawning activity. Necropsy of both live and dead fish revealed no gross lesions. Histologically, the intestines had mild to moderate necrotizing enteritis. Several bacterial agents were isolated from the intestine in high numbers, but only Citrobacter freundii was also isolated from additional tissues, and is believed to be the causative agent of mortality in this case. Based on sensitivity results, oxytetracycline treatment was initiated, and marked improvement in signs and decreased mortality resulted. Citrobacter is an opportunistic pathogen in the family Enterobacteriaceae, closely related to Salmonella. While well known as the cause of transmissible murine colonic hyperplasia, as well as enteritis and neonatal meningitis in humans, this organism is beginning to be more frequently isolated from various fish species.   Return to 23rd Annual Eastern Fish Health Workshop Return to Leetown Science Center Home Page