Submitted to: Journal of Fish Diseases
Publication Type: Peer reviewed journal
Publication Acceptance Date: 1/27/2012
Publication Date: 8/1/2012
Publication URL: http://handle.nal.usda.gov/10113/55631
Citation: Darwish, A.M., Bebak, J.A., Schrader, K. 2012. Assessment of Aquaflor (c), copper sulfate and potassium permanganate for control of Aeromonas hydrophila and Flavobacterium columnare infection in sunshine bass, Morone chrysops female x Morone saxatilis male. Journal of Fish Diseases. 35:637-647. Interpretive Summary: Aeromonas hydrophila and Flavobacterium columnare are ubiquitous bacteria in the aquatic environment. Both bacteria have been recently ravaging the sunshine bass industry in the United States, causing significant uncontrolled mortalities. In the current study, the effectiveness of florfenicol antibiotic, copper sulfate and potassium permanganate were tested against natural experimental infection of A. hydrophila and F. columnare in sunshine bass. Florfenicol was clearly effective in reducing the mortalities caused by the bacteria while the copper sulfate results were inconclusive. This prompted further testing of copper sulfate against an experimental infection of A. hydrophila and F. columnare. Copper sulfate was demonstrated to be affective against these bacteria. Florfenicol and copper sulfate were capable of curbing the mortalities caused by these bacteria in sunshine bass. The results provide the US aquaculture industry with a much needed tool to control the mortalities caused by A. hydrophila and F. columnare infection in sunshine bass.
Technical Abstract: Two experiments were conducted to assess different therapeutants against a mixed infection of Aeromonas hydrophila and Flavobacterium columnare in sunshine bass (SB) (Morone chrysops female x Morone saxatilis male). Experiment 1 assessed the efficacy of copper sulfate (CuSO4), florfenicol-medicated feed and potassium permanganate (KMnO4) against a natural mixed infection. Experiment 2 further evaluated CuSO4 as a treatment to control an experimental mixed infection. In Experiment 1, naturally infected SB were randomly assigned to one of six treatments: 1) untreated control, 2) florfenicol medicated feed at 15 mg kg-1 body weight for 10 d, 3) and 4) waterborne exposure to CuSO4 for 24 h at 2.1 or 4.2 mg L-1 (1% or 2% of the total alkalinity, respectively), or 5) and 6) waterborne exposure to KMnO4 at 2 mg L-1 above the KMnO4 demand (PPD) for 24 h, or 10 mg L-1 above the PPD for 1 h. At the end of experiment 1, percent survival was lowest for the control treatment, at 71%, and was 88% and 79% for the CuSO4 treatments at 1% and 2% of the total alkalinity, respectively. Percent survival was 72% and 77% for the 2 and 10 mg L-1 KMnO4 treatments, respectively. The florfenicol treatment had 90% survival, which was significantly greater than the control treatment (P < 0.1). The survival curves for the florfenicol treatment and the CuSO4 treatment at 1% total alkalinity were significantly improved from the control treatment. Experiment 2 had four treatments: two treatments of fish challenged by waterborne exposure to A. hydrophila and F. columnare and either not treated or treated with CuSO4 at 1% of alkalinity; and two treatments of unchallenged fish either not treated or treated with CuSO4 at 1% of total alkalinity. At the end of experiment 2, the percent survival of the challenged fish treated with CuSO4 (99%) was significantly higher (P < 0.05) than the challenged non-treated fish (61%). The results of experiment 1 and 2 illustrate clear benefit of FFC and CuSO4 against a mixed infection of A. hydrophila and F. columnare.