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Experimental Infection of Indigenous Climbing Perch Anabas Testudineus with Aeromonas Hydrophila Bacteria

M. Farhad Hossain
Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

M. Mamnur Rashid
Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

M. A. Sayed
Department of Aquaculture, Bangladesh Agricultural University, Mymensingh-2202, Bangladesh

Abstract/ Executive Summary:

The present study was conducted to know the pathogenicity and LD₅₀ of Aeromonas hydrophila isolated from diseased climbing perch Anabas testudineus against apparently healthy homologous fish and the distribution of the bacteria in the organs of the experimentally infected fish. A total of 10 fish of average body weight of 18 g were used. For pathogenicity test, two different doses viz. 9.2 × 107 and 9.2 × 106 CFU/fish were injected intramuscularly. Pathogenicity of A. hydrophila was confirmed at water temperature of 28.53^oC by the mortality of 40% to 100% of all tested fish within 4 to 9 days. The highest bacterial load was found to be 9.4 × 108 CFU/g in the intestine and the lowest bacterial load was found to be 2.8 × 103 CFU/g in the kidney of the tested fish. Four different serial concentrations, vide 9.2 × 107, 9.2 × 106, 9.2 × 105 and 9.2 × 104 CFU/fish of the bacteria were injected in each of four different groups of 10 fish. The calculated LD₅₀ value at 27.3^oC water temperature was 2 × 107 CFU/fish of 18 g of average body weight. In all the cases of intramuscular injection, external pathology was found. Reddish anal region and fin bases were observed. Injected A. hydrophila was re-isolated from liver, kidney and intestine of the challenged fish. It was understood that the isolate was a high virulent pathogen for A. testudineus.

Keywords: LD50, Aeromonas hydrophila, Anabas testudineus, Pathogenicity

Location: Wet laboratory and fish disease laboratory of the Department of Aquaculture, Bangladesh Agricultural University, Mymensingh.

Start Date: 00-07-2010

End Date: 00-12-2010

Program Area: Pest Management

Commodity: Koi/Climbing

Objectives:

To know the pathogenicity of A. hydrophila in Anabas testudineus.

Methodology:

Apparently healthy indigenous climbing pearch Anabas testudineus (koi) were collected from different fish markets of Mymensingh stocked in cemented cistern and acclimatized for 15 days providing adequate feed and better aeration by circulating water. A Celsius thermometer was set with an aquarium for temperature recording. The infection experiments were conducted at the wet laboratory and fish disease laboratory of the Department of Aquaculture, Bangladesh Agricultural University, Mymensingh. Duration of the experiment was 6 months from July to December 2010. In the Wet laboratory, a recycle system was set with having 150 l capacity drums, filled with coconut straw for filtering of bacteria. Twelve aquaria of fiber glass each having 40 l capacity, an over head tank and an ultraviolet tube light complex chamber for disinfection had the access to an electric pump. The recycle system was filled with both pond and supply water. Prior to the experiment the water was kept under circulation for 7 days. For the pathogenicity experiment, intramuscular injection method was used to know the efficacy of the method in initiation of infection and pathogenicity of the pathogen. An amount of 10 mg of fresh culture of the bacteria was carefully scraped and mixed with 1 ml PS and desired dilutions were prepared by serial decimal dilution method. In a preliminary test the above stock dilution (10 mg in 1 ml) was calculated to contain around 107 CFU/ml. Four serial dilutions having an estimated concentration of 107, 106, 105 and 104 CFU/ml were used for the (LD50) experiment. From each of the above 4 dilutions, 0.1 ml bacterial suspension was injected intramuscularly to each of previously stocked and acclimatized 10 fish making a group.

Source of Information: Progress. Agric. 22(1 & 2): 105 – 114, 2011 ISSN 1017-8139

Article Link (Online Journal):

Funding Source:

Total Budget (Tk.) :

Achievement/Findings:

It was confirmed that A. hydrophila bacteria was found to be a serious pathogen for the climbing perch as was also found for carps, catfishes, eels and snakeheads. Pathogenesis of A. hydrophila in the liver, kidney and intestine was very active. Further researches are necessary to prepare antibody against this bacteria, to serotype all Bangladesh isolates, to prepare whole vaccines and purified vaccines and to try vaccination in susceptible fishes to save our fish folks against this pathogen.

Knowledge Management: Journal