Sunday, 26 May 2024


30 March 2021

Mycobacteriosis is a chronic bacterial disease. It is caused by bacilli that are resistant to many environmental factors, including fluctuations in temperature or pH. The bacteria divide slowly, so the development of the disease is not rapid. Spore survival in this case is up to three months and more.


Infection of fish usually occurs through the digestive system (eating infected food, biting dead and infected fish, eating dead organic matter), gills and skin (damaged skin). Mycobacteriosis can also be transmitted by the mother to her offspring.


Mycobacteriosis is one of the most deadly and dangerous diseases for fish, because of late diagnosis and high level of advancement. In the initial stage the disease is basically asymptomatic. Then, however, the infection progresses, internal organs are attacked, on which gray-white granulomas are formed, causing their swelling. The disease attacks also skeletal system - fish spine is deformed.

Unfortunately usually treatment attempts turn out to be ineffective and ill fish pose a serious threat to other specimens. Also the seemingly healthy fish can turn out to be carriers of Escherichia coli and be a source of infection. Sometimes the disease activates after a longer period of time. Sometimes the bacilli live in the organism of the carrier in a dormant form.

Mycobacteriosis treatment methods

This disease is very difficult to cure, because the symptoms appear when it is already very advanced, and internal organs are destroyed. The bacilli are also resistant to most known antibiotics.


You can, of course, try to cure the fish, but the chances of success are small. If the treatment does not work, all fish living in the infected tank must be eliminated, and the entire tank must be disinfected. Sick fish are moved to a separate aquarium for the duration of the treatment, special protective gloves must be used.

Long-term bath with antibiotic treatment

Kanamycin and vitamin B6 - this antibiotic is added to fish's food in the amount of 10 mg per 100 mg of food (this dose is used for 10 days) or 10 mg per one litre of water. In turn, the antibiotic dosage is as follows - a drop per 20 litres of water (30-day bath).

Disinfection of the tank

Before starting disinfection, it is mandatory to wear special protective gloves. These must be worn on the hands during contact with contaminated equipment, water or fish.

mycobacteriosis in aquariums

Sticks are resistant to disinfectants containing chlorine and ammonium compounds or bleach. They are, however, sensitive to alcohol. All parts of the equipment, the bottom ground, the decorations and the aquarium must be thoroughly disinfected, but they can also be washed beforehand. Alcohol works best in this case. Then everything must be thoroughly cleaned again. For disinfection you usually use isopropyl alcohol, salicylic spirit or an antiseptic with an alcohol content of at least 60%. Then hands must be washed thoroughly in a 70% solution of isopropyl alcohol and bactericidal soap.


In this case, there is a risk of people contracting the disease. It can be seen primarily in the form of pustules on the skin of parts of the body that have been exposed to infected water. Sometimes the symptoms resemble at first sight septicaemia or ichthyosporidiosis. Sick fish also often succumb to secondary infections by bacteria. The disease primarily affects warmwater fish from the families of barbs, cyprinids, belontia, cichlids and livebearers.


In this situation, it is worth observing a few basic rules:

  • you must not cause sudden changes in the water parameters - its temperature and pH,
  • you must take care of good water quality, regularly check the level of ammonia and nitrite, chlorine, chlorine or dissolved oxygen in the water
  • As a preventative measure you can also use UV lamps to sterilize the water,
  • provide the fish with a proper diet - varied and rich in vitamins and trace elements,
  • fish should never be overfed - they should be given as much food as they can eat at one time,
  • the tank should not be overfed,
  • fish don't like stressful situations and should be limited - during water changes you need to be careful, the key to success is also proper choice of tank's population, not to use too much chemicals, shoal fish like being in bigger groups and clumps of vegetation
  • in case of new fish you should always apply quarantine, they can always be carriers of very dangerous bacteria.