| dc.description.abstract | Vietnamese Koi (Anabas testudineus) is considered as a high value fish species in
Bangladesh. The fish contains high amount of iron and copper, which are nutritionally
beneficial for hemoglobin synthesis in human. A total number of hundred seventy five
of infected /dead V. Koi fishes were collected during outbreak period from seven
different areas in Mymensingh district for conducting this study. The main purpose of
this study was to isolate and identify the bacterial spp. responsible for mass mortality
of V. Koi from selected outbreak areas in Mymensingh district and to know the
pathogenicity of the isolated bacteria. The main clinical symptoms were hemorrhage
in base of the fin, slight lesion on body, body and tail erosion. Post-mortem changes
indicated congestion and enlargement with hemorrhage in liver, kidney and spleen
.Isolation and identification of bacteria was conducted by studying cultural properties,
gram staining and biochemical properties. Biochemical tests for bacteria which were
performed by API kit indicated positive results by reacting with betagalactosidase,
arginine dihydrolase, lysine decarboxylase, sodium citrate, tryptophan deaminase,
sodium pyruvate, gelatinase, glucose, mannitol, sucrose, melibiose, amygdalin, and
arabinose for all isolates. And showed negative result when tested for ornithine
decarboxylase, H2S production, inositol, sorbitol, and rhamnose. Among the various
isolated bacteria, Aeromonas hydrophila and A. caviae were appeared as main
pathogen in the infected fishes. Total bacterial load found at 1.13×106
to 3.21×108
cfu/g in lesions; 1.10×105
to 2.1×107
cfu/g in liver; 3.24× 04
to 3.82×106
cfu/g in gill;
1.25×106
to 3.51×107
cfu/g in kidney and 3.74×104
to 2.43×106
in spleen of diseased
Koi. Cumulative mortality rate was recorded the highest (89%) at the group 2 after 14
days of post inoculation because of the infection of Aeromonas hydrophila.
Commercially available antibiotics were used for the determination of sensitivity test
for the isolated bacteria. All the isolated bacteria were found sensitive to
endrofloxacin, ciprofloxacine, levofloxacine, azithromycin and gentamicin.
Ciprofloxacine and levofloxacine were highly effective against A. hydrophila and A.
caviae. Ampicillin & penicillin did not show any activity against Aeromonas spp.
Study indicated that motile Aeromonas sp. perhaps serve as the primary cause of
hemorrhages, ulcerations and skin lesions as well as mortality of V. Koi. The result of
this study will be useful for V. Koi aquaculture by applying right antibiotics against
Aeromonas spp. in order to prevent mass mortality. | en_US |
