Something nasty in your water?

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Vet William Wildgoose explains why you should take extra care when maintaining your aquarium.

A zoonosis is the term that describes an infectious disease that spreads from animals through to humans and vice versa — such as coming into contact with infected fish water.

Mycobacterium, the bacteria that cause TB in fish, is one of the few common zoonotic infections in the hobby, and is a very good reason to take extra care when carrying out maintenance on your fish tank.

What signs will a fish show of having TB?
The bacteria will cause a chronic disease over weeks and months, resulting in abscesses throughout the body.

The symptoms will depend on which organs are affected and can physically appear as weight loss, colour change, skin sores and abdominal swelling.

Many small fish may show no specific outward signs but die after displaying lethargy and showing anorexia.

Diagnosis requires an autopsy and laboratory tests to identify the lesions and bacterial organism.

There is as yet no effective treatment for the disease, which can persist in fish and in its water for many months.

How do fishkeepers become infected and what are the symptoms?
Fishkeepers will get infected through direct contact with that infected water, particularly if they have open skin wounds.

In humans, the organism generally produces chronic skin lesions on the hands and arms. These fail to heal and may require months of treatment.

These will often resemble other types of skin disease, may initially be misdiagnosed and require a dermatologist’s opinion in order the pinpoint the cause.

Humans who are immuno-compromised following chemotherapy or have HIV infections are at more risk of contracting zoonosis and may develop a life-threatening illness.

How can I reduce the risk of catching a zoonosis?
Hobbyists can practise good hygiene, such as wearing arm-length gloves or thoroughly washing any exposed skin with antibacterial soap. 

You should never prime syphons by using your mouth.