Infected animals usually show a lack of appetite

The Fish tuberculosis is a bacterial infectious disease, which occurs mainly in fish in aquariums. It is widespread. Leads to large losses. The disease of free-living fish is possible, but rare.

The disease occurs in both freshwater and saltwater fish, with infections being most common in tetras and rare in catfishes.

The pathogens are various species of mycobacteria, with Mycobacterium marinum, M. fortuitum and M. chelonae are particularly frequently involved. These bacteria are widespread in the aquatic environment. Their mere presence does not generally lead to disease. For an infection further favorable accompanying circumstances are necessary. This may be due to stress caused by overstocking or lack of cleanliness in the aquarium, for example.

In general, the risk of infection is increased by unfavorable husbandry conditions. The disease is usually introduced into an aquarium by new arrivals. The pathogens can also survive saprophytically in the mud or mulm of the aquarium.


The manifestations of the Fish tuberculosis are very diverse and make diagnosis on live fish difficult. The Fish tuberculosis progresses chronically in most cases.

Chronic course

The gradual loss of individual animals from the stock over a long period of time is the rule. Typical are tubercles surrounded by a connective tie capsule.

In younger tubercles, acid-fast rods are still easy to find, in older tubercles their number is significantly lower.

Acute course

This form of the disease is characterized by extensive, exudative foci of inflammation. In case of a sudden flare-up of the infection, e.g. due to unusual stress, a total loss within one or two weeks is possible.

Affected animals usually show a lack of appetite, become apathetic and lose weight. Inflammations of the skin with ulceration develop. The fins regress. In addition, "goggle eyes" (exophthalmos), panophthalmitis (disease of the entire eye) up to the loss of the eye, scale defects, fading of the color, crippling of the spine and jaws, abdominal dropsy (ascites) and behavioral changes may occur.

On dissection of an infected animal, whitish-gray granulomas are found in almost all organs, especially the spleen, kidney, and liver. In the case of the acute course, the viscera are often agglutinated as a result of peritonitis. The rod-shaped pathogens are intra-. Extracellular masses can be detected.

Diagnosis and therapy

The diagnosis is made by histological evidence of tuberculous granulomas. Since the pathogens can also be part of the normal intestinal flora, their presence without pathological tie changes is not sufficient proof of a disease. Differential diagnosis must be made especially infections with Nocardia, Ichthyophonus and Aeromonas ssp. which can also be accompanied by granulomas should be excluded.

Although there are occasional reports of treatment success with antibiotics, the Fish tuberculosis currently not treatable with medication. The focus must therefore be on preventing an outbreak by optimizing husbandry conditions as much as possible and quarantining new additions for four weeks. Therefore, in case of acute course, the control is carried out by killing the stock. Elimination of the furnishing of the aquarium realized. Afterwards a disinfection of the aquarium is necessary. Of the technical furnishings displayed. In chronic cases, the removal of diseased animals may be necessary. Optimizing the housing conditions is sufficient.

Danger to humans

That the Fish tuberculosis causative Mycobacterium marinum can be transmitted to humans and other mammals through minute skin lesions. In humans, these infections cause the so-called swimming pool or aquarium granuloma (ICD-10: A31.11 Infection by Mycobacterium: marinum).

This is a granuloma that is confined to the skin and can be persistent. Therapy usually shows rapid success. If left untreated, spontaneous healing usually occurs after one to two years. A treatment should be carried out nevertheless, in order to avoid a germ spreading. For prevention, it is advisable to wear protective gloves when cleaning aquariums. This article was taken from the "German Wikipedia taken from. Is under this use license.

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