Betta Tuberculosis: Everything You Need To Know

betta tuberculosis
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Last Updated: August 22, 2023 by Flora Gibbins

It is sad when a once active, colorful betta looks sickly. If you suspect your fish has betta tuberculosis, there is not much you can do at this point.

Do you know why?

Bettas are among the main carriers of tuberculosis, and the rising number of bacterial infections is making fish owners worry.

But what exactly is fish tuberculosis? How do bettas contract tuberculosis? What are the classic symptoms of fish TB? Is it preventable?

This guide provides detailed answers to these questions and more. Read on.

What is Betta Tuberculosis?

sick bettas in aquarium

Tuberculosis is a rare bacterial infection that affects both freshwater and saltwater fish. Though rare, there are chances that your fish can become sick.

Betta Tuberculosis is caused by a mycobacterium naturally present in some aquariums.

The most common mycobacterium is Mycobacterium Marinum, similar to the human TB bacterium (Mycobacterium tuberculosis).

Other responsible mycobacteria include Mycobacterium gordonea, Mycobacterium frotinum, Mycobacterium chelonae, M. avium, M. trivale, M. peregrinum, and M. abscessus. Each of these pathogens has different symptoms which makes it difficult to point to fish TB. The symptoms are often mistaken for common fish diseases because they are similar.

Betta TB is a slow blooming disease that takes up to 6 months before any clinical signs manifest.

This means that it is easy to miss it during the quarantine period which often lasts a week or two.

The mycobacterium Marinum slowly infects the fish’s internal organs, making it deadly. By the time you note the first symptoms, your betta’s organs are already failing, reducing the likelihood of survival.

Tuberculosis is highly contagious. Your sick betta can easily transfer the infection to other fish, and at times, humans too.

But what causes this deadly tuberculosis among healthy fish?

5 Common Causes of Fish Tuberculosis

betta fish in aquarium with drift wood

Keeping in mind that your fish tank may be harboring Mycobacterium Marinum, some factors may influence your betta to catch the disease. The common causes of fish tuberculosis include

  • Poor breeding methods
  • Poor water quality
  • Diet
  • Stress
  • Introduction of infected fish or aquarium equipment

Poor Breeding Methods

different betta species

Today, some fish breeders are in the business to make money. Therefore, they do not prioritize the overall health of the fish they breed. Poor breeding methods contribute to unhealthy bettas right from birth. Since these fish are genetically weak right from birth, they become more susceptible to catching the tuberculosis mycobacterium.

Poor Water Conditions

red betta fish with plants

Poor water quality also causes tuberculosis in fish. If your tank is overstocked, chances are your filter is not providing adequate filtration to remove the excess bioload. Ammonia build-up from the bioload affects water quality in the aquarium, and in turn, weakens the immune system of your betta. When this happens, it becomes easy for your fish’s body to catch tuberculosis.

An unclean aquarium could also be the cause of betta TB. When you do not perform regular water changes, cleaning routines, or vacuum the gravel, your pet is likely to contract tuberculosis.

Additionally, fluctuating water conditions can cause tuberculosis in betta fish. High temperatures provide perfect breeding conditions for the bacteria. Sadly, bettas get stressed out when the temperatures and pH levels in their aquarium keep fluctuating. Due to this, the betta fish will get sick and contract tuberculosis and other infections.


red bloodworms food for bettas

Bettas thrive on live food to stay healthy. However, if this live food is infected with TB, the betta will likely catch fish TB through digestion

Additionally, bettas eat other fish. If a betta eats a fish that died of tuberculosis, it too may contract tuberculosis. Moreover, a poor diet will weaken your pet’s immune system and increase the likelihood of having a sick betta.


siamese fighting fish white blue with dots

There are lots of things that can stress a betta fish, including fluctuating temperatures and pH, high ammonia levels, low oxygen levels, incorrect salt levels, high nitrate levels, incompatible tank mates, and more.

When a betta is stressed, its immune system gets compromised. Without a strong immune system, the fish is likely to catch tuberculosis.

New Introductions

New fish can harbor tuberculosis and introduce it to your main aquarium. This is why it is recommended to house these fish in a quarantine tank for observation, even when they look healthy.

Additionally, using contaminated tank equipment in your main tank can also introduce bacteria.

Symptoms of Tuberculosis in Betta Fish

Most symptoms of fish tuberculosis mimic other less severe illnesses, making it difficult to diagnose. The bad news is you will likely catch the symptoms when it is too late, and at this stage, your fish’s organs will be failing.

Nevertheless, it is worthwhile to know what signs to look for.

Skin Defects

Betta tuberculosis causes the loss of scales, a definitive symptom of this fish disease. Other symptoms include skin lesions, wasting of flesh, and raised scales (pine-coning). Your betta may also have discoloration, open wounds, folded fins, and blood spots.

Curved Spine

A betta’s curved spine is another indication of fish tuberculosis. Betta’s spine curve vertically instead of the sides to show the extent of organ failure. A betta fish bent spine can also be a sign of spine infection.

Sluggish Movement

Bettas with tuberculosis have sluggish movement or no movement. Healthy bettas are energetic and love exploring their environment. However, when a betta becomes less energetic or simply floats at the top of the aquarium, it is evident they are sick.

Nevertheless, lethargy does not mean fish disease. This symptom is common with other diseases, tuberculosis included.

Loss of Appetite

Bettas with fish tuberculosis have a poor appetite and gradually become anorexic. Your betta may lose weight to look emaciated. Loss of muscle mass is associated with tuberculosis, but it may also be a symptom of other illnesses.

Eye Damage

If your betta currently has protruding eyes or they are discolored, they have probably contracted tuberculosis. This is often a result of swollen organs behind the betta’s eyes. However, eye damage may also be caused by popeye disease.

Other symptoms include:

  • Ulcers
  • Edema
  • Growths
  • Bloat
  • Sunken belly
  • Nodules in the muscles
  • Bones sticking out
  • White feces/stringy poop
  • Clamped fins

The most effective way to determine betta tuberculosis is to examine the internal organs. Infested organs have white or grey nodules. Unfortunately, this examination can only be done on a dead betta.

Can You Treat Tuberculosis?

Fish tuberculosis is incurable.

The condition only manifests when the internal organs are failing, making it life-threatening.

Despite popular belief, antibiotics and penicillin do not treat fish tuberculosis. Why? Because this treatment plan has minimal chances of success due to the extensive damage to the internal organs.

Traditional methods, like increasing tank water temperature or adding aquarium salt are ineffective too. Warm temperatures do not deter the population of mycobacterium Marinum. Instead, it provides better breeding grounds. On the other hand, aquarium salt neither improves nor worsens the condition of the aquarium.

However, if you observe the first symptoms in the early stages, it is possible to manage them. Some common symptoms include anorexia, raised scales, sunken belly, and clamped fins. Since TB mimics other bacterial infections, you can ask your vet to prescribe the right medication or appetite stimulant.

We recommend that you follow these steps when implementing a treatment plan:

Step 1: Move the sick fish into a quarantine tank once you observe the symptoms.

Step 2: Add an air stone and a cycled gentle filter into the aquarium.

Step 3: Add the prescribed medication into the hospital tank as directed by your aquatic vet.

Step 4: Incorporate a fish bath using methylene blue.

If the above steps do not improve the symptoms of your fish, consider euthanizing them. TB symptoms are painful as the fish’s health deteriorates, making euthanizing a merciful alternative.

Factoid: Remedial cures won’t help your betta if tuberculosis is in its advanced stages. The only method to help your pet is through euthanizing. Learning To Euthanize A Betta Fish – Ways And Reasons Why will relieve it from further suffering and pain.

How To Clean An Infected Betta Tank

If you are certain that your betta fish have fish TB, it is best to clean the infected tank. How?

Step 1: Move the sick fish into a hospital tank.

Step 2: Dispose of infected porous materials since they cannot be cleaned effectively.

Step 3: Consult your vet for the best effective bleach solution to kill the bacterium and sanitize the tank.

Only use treatment products recommended by a professional when cleaning and disinfecting the tank. Your goal should be to recreate a healthy environment for your betta fish.

5 Ways To Prevent Betta Tuberculosis

It is possible to prevent fish TB. Remember, this disease is rare even though the bacteria responsible is always present in the fish tank.

Here is how you can prevent it:

1. Feed Reliable Live Food

It is crucial that you only feed your pet live food from reliable suppliers. Some best live foods include vinegar eels and micro worms because they do not carry tuberculosis. You can also opt for frozen live food.

2. Buy Fish from Reputable Suppliers

Some pet store water tanks are contaminated with certain strains of tuberculosis pathogens. When you buy a fish from these retailers, all your aquarium needs is a single carrier fish to introduce the disease. This is why you should only purchase fish from reputable pet shops.

3. Quarantine New Fish

After buying new fish, quarantine them before adding them to your tank. Leave them here for 2 to 4 weeks as you monitor their health.

4. Maintain Good Water Conditions

When you maintain the ideal tank conditions for your betta, they are unlikely to catch tuberculosis. Make sure you perform two water changes and gravel vacuuming once a week if you own a smaller tank. Also, provide just enough food. Overfeeding will only boost the overgrowth of bacteria.

5. Improve Betta’s Immune System

As previously noted, a betta with a weakened immunity is more likely to get tuberculosis. Therefore, always offer your betta fish a healthy diet, avoid housing them with harsh tank mates, and keep their aquarium conditions pristine. A stress-free betta is a healthy fish.

Can Humans Catch Fish Tuberculosis?

Yes. Fish tuberculosis can be transmitted to humans. Fish owners, particularly those with a compromised immune system can easily contract this slow blooming disease.

Additionally, since the bacteria can travel through open cuts, placing hands with open wounds in the aquarium can cause TB. You can also catch fish tuberculosis by sucking on a siphon and ingesting the contaminated water.

If you catch betta tuberculosis, also known as fish keeper’s disease, you’ll get itchy, painful, and persistent skin infections. This is because the bacterium gets into your body through the skin, hence the dermatological problem. Fortunately for you, tuberculosis is not a death sentence.

But you can avoid this nasty experience altogether. First, always wear gloves every time you put your hands in the betta aquarium. Second, thoroughly wash your hands after touching aquarium water. Third, avoid sucking siphons with your mouth. And lastly, practice good tank hygiene.

And before we wrap this thing up, here’s a video about Betta Tuberculosis:

Final Thoughts

Fish tuberculosis is life-threatening among bettas and other fish. It is difficult to diagnose because its symptoms are similar to other illnesses. Moreover, most fish die even after following a treatment plan with an aquatic vet.

Nevertheless, you can prevent tuberculosis by feeding live food from reliable sources, maintaining perfect water conditions, and limiting any stress factors for your betta. Remember, it is unlikely for a healthy betta to contract tuberculosis.

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