ARS | Publication request: Aeromonas hydrophila in 2010: Characteristics of Alabama outbreaks

Submitted to: Aquaculture Miscellaneous Publications
Publication Type: Trade Journal
Publication Acceptance Date: July 25, 2011
Publication Date: August 1, 2011
Citation: Bebak, J.A., Hemstreet, W., Garcia, J.C. 2011. Aeromonas hydrophila in 2010: Characteristics of Alabama outbreaks. Alabama Fish Farming Center Fish Farming News. Summer 2011. p. 1-2.

Technical Abstract: For a second year, epidemics associated with a virulent strain of Aeromonas hydrophila resulted in losses of hundreds of thousands of pounds of market size Alabama (AL) catfish. During this period, the Alabama Fish Farming Center diagnosed outbreaks of this strain of A. hydrophila on 25% (28/113) of AL catfish farms. The USDA ARS interviewed 86% (25/28) of these farmers about characteristics of these A. hydrophila outbreaks on a total of 71 ponds. Results indicated that: 1) Pond water temperatures were greater than 80ºF. For the first outbreak in April, pond water temperature was in the high 70’s (ºF). The rest of the outbreaks occurred at above 80ºF. 2) Hemorrhage in iris was a notable feature. At least 80% (20/25) of the producers noticed blood in the iris of the eyes of dead fish. 3) Fish did not reduce feeding before outbreaks. Reduced appetite was not seen by farmers for slightly more than 80% (56/67) of the ponds. 4) Fish did not need to experience a stressor before mortality started. For 79% (54/68) of the ponds, farmers did not recall that any particular stress had occurred before the mortality started. 5) Dead fish were market size and slightly smaller. For the 71 ponds, 83% (59/71) reported that mortality occurred in fish that weighed >¾ lb. 6) Most of the farmers (80%) treated the outbreaks by feeding medicated feed or applying copper sulfate pentahydrate. The outbreak was about 22% shorter if medicated feed was fed compared with copper sulfate. For either treatment, the total number of days of mortality depended on the day the treatment started.