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Various bacteria, including Aeromonas, Pseudomonas and Vibrio. |
loss of appetite
Lesions, ulcers or sores on the body
Reddening at the base of the fins and vent
Darkening of coloration
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Lesions, ulcers or sores on the body, reddening at the base of the fins and vent, loss of appetite and darkening of coloration are all symptoms of infection. Dissecting an affected fish often reveals an accumulation of fluid in the body cavity and haemorrhages among the internal organs. Ulcers may become secondarily infected with fungus. In very acute disease outbreaks, however, fish may die showing very few obvious external symptoms.
The bacteria responsible for this type of disease are often very common in the aquatic environment or as low-level 'latent' infections in otherwise healthy fish. However, outbreaks usually occur only in fish which are in poor condition for some reason, such as recent importation, rough handling or overcrowding. In a poorly maintained pond or aquarium, the disease can have devastating effects, as diseased fish released pathogenic bacteria into the water, which in turn infect other fish. |
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