Fish Tuberculosis: Causes, Symptoms & Treatment

Fish tuberculosis is a systemic disease that can occur in both freshwater and marine fish.

The disease is caused by the bacterium Mycobacterium marinum, which can spread through the water or fish food.

Fish tuberculosis is most often found in cold-water fish species, such as trout, salmon, and bass.

Infected fish may experience a variety of symptoms, including difficulty breathing, and rapid weight loss.

What is Fish Tuberculosis (Mycobacteria in Fish)

Fish tuberculosis (TB) is a bacterial infection that can occur in both warm and cold-blooded fish. It is also known as a mycobacterial infection in fish.

The disease is caused by a mycobacterium called Mycobacterium marinum, which is found in water and soil.

Fish TB is most commonly found in coldwater fish, such as trout and salmon, but it can also affect fish in warm water habitats.

Fish tuberculosis can be deadly to fish if not treated quickly.

Causes of Tuberculosis in Fish

The main cause of tuberculosis in fish is the Mycobacterium marinum bacteria. This bacterium is found in both fresh and saltwater and can cause lesions on the fish’s skin, fins, and eyes.

Other causes of tuberculosis in fish include other mycobacteria species, as well as fungi, viruses, and parasites. In severe cases, the infection can lead to death.

How Does Fish Tuberculosis Spread

These bacteria may be spread through water or food, or through contact with infected fish.

Different types of mycobacterium bacteria, like Mycobacterium marinum, M. fortuitum, and M. chelonae, can infect freshwater fish. M. marinum can be found in both freshwater and marine environments.

It is transmitted through direct physical contact and living things that die and then release the disease inside the body.

This illness is highly contagious and can pass from one fish to the next. This makes it an easy way to pass through quarantine, which typically lasts for one to three weeks.

Signs and Symptoms of Fish Tuberculosis

Mycobacterial infection usually occurs in freshwater fish as their immune systems are not fully developed. Fish tuberculosis symptoms are,

-The most common symptoms of fish tuberculosis are lethargy, loss of appetite, weight loss, and abnormal swimming behavior. In severe cases, the infected fish may have open sores on their body.

-Clamped fins (fins are closed up or folded together), fin deterioration.

-Pale body color, a dropsy-like appearance, reproductive problems, and a host of secondary infections.

-Excessive weight loss, scale loss, skin ulcers, and pop-eye.

-The pathology is usually characterized by granulomata in ectothermic fish. Nodules in muscles may deform the fish.

How Diagnosed Fish Tuberculosis

Mycobacterium marinum bacterium can affect any fish, regardless of age or size.

Fish tuberculosis is most commonly diagnosed by taking a sample of the fish’s blood or tissue and culturing it in a lab to see if the bacteria are present.

The presence of a mycobacteria strain is confirmed using an acid-fast dye.

Treatment typically involves antibiotics and/or euthanasia of the infected fish.

The disease-causing organism can often persist for many years in seemingly healthy systems.

How To Treat/Cure Tuberculosis of Fish

Infection with Mycobacterium spp, the bacteria that causes tuberculosis in fish, is a common problem in both fresh and saltwater fish.

The disease is not usually fatal if treated early, but left untreated can be deadly.

There are a number of mycobacterium fish treatments, depending on the severity of the infection.

Antibiotic Treatment

If the infection is mild, antibiotics such as erythromycin or tetracycline may be effective.

In more severe cases, antibiotics such as kanamycin or streptomycin may be necessary. Enrofloxacin at 5 – 10 mg/kg is recommended for treating tuberculosis.

Vitamin B complex and C were supplied at 0.1 mg per kilogram once a week.

Salt Bath

Salt baths are a common treatment for many diseases of fish.

The salt bath helps to draw the disease out of the fish and speeds up their healing process.

For tuberculosis, adding salt to the water can help to kill the bacteria that cause the disease.


The disease is often spread through contact with infected water or other fish, and can also be transmitted to humans.

There is currently no vaccine available for fish tuberculosis, but researchers are working on developing a vaccine using zebrafish.

Zebrafish is an ideal model for vaccine development because they are easy to work with and their immune system is very similar to that of humans.

Studies have shown that the zebrafish vaccine can protect against M. marinum infection, and further research is needed to determine its effectiveness in humans.

How to Prevent Fish Tuberculosis

There are several ways to prevent fish tuberculosis from affecting your fish tank.

Fish tuberculosis can be prevented by keeping the tank clean and free of dead fish or other decaying material, which can serve as a breeding ground for the bacteria.

You should also make sure that you are using a good quality water filter to keep the water in your tank clean.

Regular water exchange can play a great role to replace dirty water with fresh and clean water.

Feed your fish high-quality nutritious food.

Fish Tuberculosis in My Tank/Aquarium

Betta fish are particularly susceptible to TB, and outbreaks of the disease have been reported in both wild and captive populations and aquariums.

The symptoms of TB in Betta fish include loss of appetite, weight loss, lethargy, gasping for air at the surface of the water, and red or swollen gills. In severe cases, fish may die from the disease.

Different aquarium fishes are affected by this bacteria. For example betta fish tuberculosis, guppy fish tuberculosis, etc.


Is Mycobacteria dangerous to humans?

Mycobacterium marinum (nontuberculous mycobacteria) can cause a tuberculosis-like illness in fish and can infect humans.

The infection is rare, but the bacteria can easily enter into open wounds or cuts that are placed in fish tanks.

Is fish tuberculosis contagious to other fish?

There is a lot of concern about fish tuberculosis (TB) because it can be contagious to other fish. While there haven’t been any studies that prove conclusively that fish TB can be transmitted between fish, the evidence seems to suggest that it is possible.

Fish TB can be spread through water, food, or contact with infected tissues.

It is also possible for fish to become infected through skin lesions or open wounds. The symptoms of fish TB include lethargy, loss of appetite, scales standing on end, and lesions on the skin.

If you think your fish may have contracted fish TB, you should consult with a veterinarian as soon as possible.

Final Words

In conclusion, tuberculosis is a serious disease that can infect many different species of animals, including fish. The disease can cause lesions and other health problems in infected fish and can be deadly in some cases.

There is no cure for tuberculosis, but it can be treated with antibiotics if it is caught early. Fish owners should be aware of the signs of tuberculosis in their fish and seek veterinary help if they suspect their fish may be infected.