Can I Catch Tuberculosis From My Pet Fish?
Tuberculosis: Important Points of Discussion
This is what we'll be covering in this article:
- The differences between human and fish tuberculosis
- Where it comes from and how it infects a tank
- How fish TB crosses the species barrier
- Species affected by the disease
- Symptoms in humans and fish
- Treatment and prevention
The Difference Between Tuberculosis in Fish and Humans
Human TB is a serious condition and at the moment, treatment remains long and difficult. The disease scars lung tissue and can lead to death. Interrupted treatment can result in immunity against medication and unfortunately, there's also a strain of TB that's naturally resistant to drugs.
The highly infectious tuberculosis that remains epidemic in many countries is not the same thing that affects fish. That's the good news; it's not actually tuberculosis. Both diseases are caused by closely-related bacteria. Human TB results from Mycobacterium tuberculosis and fish TB from Mycobacterium marinum. The bad news is that it's indeed zoonotic (a disease that can jump from animals to people). Fish TB ravages an aquarium and causes persistent skin infections in humans. When it blooms in a person, it's also called “Aquarium Granuloma” or “Fish Tank Granuloma.”
Where Does It Come From?
You have a great collection of fish. This healthy shoal always enjoyed a clean tank and good food. Suddenly, fish sicken and a paper cut on one finger develops an agonizing infection. Out of the blue, your aquarium has tuberculosis. How did that happen? Unfortunately, fish TB can sneak past the unwary owner. Here's how:
- Adding new, infected fish (symptoms can be delayed and make a fish appear healthy)
- The new fish is healthy but the bacterium arrives in the bag of water it's sold in
- Contaminated commercial food
- Using another keeper's contaminated equipment
Marinum can live in a tank and not cause wholesale destruction. It's most likely to happen when the bacterium enters a wound, fish are genetically weak, already suffer from stress, other bacterial infections or live in substandard conditions.
A Vulnerable Fighter
The Symptoms of Fish Tuberculosis
It's important to understand that fish TB must be correctly diagnosed. There are other conditions and diseases with similar or identical symptoms. Misdiagnosis leads to the wrong treatment and possibly losing the fish to factors other than marinum. Classic symptoms of fish TB are listed below.
- A tendency to thin has earned fish TB the nickname of the “Wasting Disease” and is often the only symptom that shows
- White growths or lesions on the body
- The loss of scales
- Discolouration of scales
- Deformities, especially along the spine
- Ulcers on the flanks or head
- Bulging eyes, one or both
- Abnormal behaviour
Humans normally catch marinum while cleaning a tank if there's some kind of wound on the hand. The bacterium enters the skin and causes purple lesions. There's never been a case of human-to-human transmission of fish TB, which is treatable with antibiotics.
How to Treat Fish TB
Marinum has one thing in common with human TB; it's long and difficult to treat. Unfortunately, most antibacterial products bought over the counter won't be enough. Once the disease is positively identified, sometimes with the help of a veterinarian, the owner needs to prepare for months of changes, medication and sober expectations. For this reason, many choose to make a clean break and start fresh, with new stock and an aquarium. But for those who don't wish to discard equipment nor euthanize fish, there are options.
Gouramis Are on the List
1. The Hospital Tank
Any serious fish hobbyist must eventually own a separate “hospital tank” to quarantine symptomatic fish. To prevent cross-contamination, maintenance is done with equipment never shared with the main aquarium. The TB fish must feel as stress-free as possible since stress can push it past the point of saving. If it loves vegetation or hiding places, make sure there are plenty of them. Ensure water conditions and temperature suit the species and then place the fish inside for observation, treatment or both. A written log can track the progress of the patient.
2. The Main Tank
After removing sick fish from the main tank, decide on whether to cleanse the main tank or not. If the other fish are clearly healthy, the only step some owners prefer is to keep them under observation. However, most people prefer to not take any chances. Substrate and plants are replaced, the tank and equipment are sterilized and the fish can also be given a supplement or treatment to keep them in peak condition.
3. The Right Medication
There's no way around this one. If you skip the correct antibiotics and use cheap pet store products or home remedies, the survival rate shrinks like its being paid. Three of the best antibiotic therapies available for fish TB are Neomycin, Kanamycin and Isoniazid. However, you need professional medical advice on how to administer them and in what combination.
4. Realistic Expectations
Marinum is difficult to treat. Period. Under the best of conditions, survival expectations are below fifty percent. Stress, poor immunity and incorrect tank conditions can make treatment useless. If you have a hospital tank with optimal conditions, good food and the right antibiotic program, then do what you can. In addition, don't expect treatment to last a few days or weeks. Fighting fish TB can take three or four months of steadfast adherence to your regime.
How to Prevent Fish TB
Three things can prevent a lot of heartache and expenses. Correct conditions, a balanced diet and a beady eye. A healthy fish goes a long way to fight off this zoonotic bother, so make sure the environment is perfect: temperature, oxygen, PH levels, cleanliness and no overcrowding. Feed it the best food you can afford and no, a flakes-only diet is not healthy. A sharp eye is needed to pick up on symptoms as early as possible in order to remove a fish to the hospital tank the moment it looks off. You also need that eye when looking to purchase disease-free fish (try to avoid pet stores). When bringing home a new pet, place it in a separate quarantine tank for a few weeks just to make sure. A human infection can take months to cure, so prevention for yourself is just as important. Always wear gloves during tank maintenance.
Did You Know?
- Cows also carry a strain of tuberculosis that can infect humans.
- Nearly all aquarium fish can develop fish TB, but for some reason guppies, Siamese Fighting Fish (Bettas) and Gouramis are more susceptible.
- Confirmed cases of humans infected with fish TB are incredibly scarce—most owners can keep fish for a lifetime and never get it.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.
© 2018 Jana Louise Smit