Synonyms: Fish tuberculosis, piscine tuberculosis, acid-fast disease, granuloma disease.

Mycobacteriosis is worldwide in distribution.  All fish species should be considered susceptible.  Some are more susceptible than others, like gouramis, neon tetras, discus and labyrinth air breathers.

Clinical Signs:

Mycobacteriosis is a chronic progressive disease.  It may take years for it to develop into a clinically apparent illness.  Some signs to look out for include: Lethargy, anorexia, fin and scale loss, exopthalmia, emaciation, skin inflamation and ulceration, edema, peritonitis and nodules in muscles that may deform the fish.

Examinations usually reveal gray or white nodules in the liver, kidney, heart or spleen.  There also may be skeletal deformities.  Diagnosis is usually based on clinical signs and the presence of acid fast bacteria in tissue sections.

Mycobacteria are gram-positive, pleomorphic rods that are acid-fast and nonmotile.  They form cream-colored to yellow colonies on solid media.   It is suggested that transmission of this disease may be caused by contaminated food.

infection rates can be quite high in contaminated freshwater tropical fish production facilities.  The aquatic environment is considered the reservoir.  Mycobacterium marinum has been cultured from swimming pools, beaches, natural streams, estuaries, tropical fish tanks and city tap water.  Human epidemics of granulomatous skin disease have occurred from swimming in infected water.  This mode of human infection is much more common than infection from exposure to infected tropical fish tanks.  This disease will usually attack a sore or abrasion and be apparent about 2-3 weeks after exposure.

Treatment and Control:

Kanamycin + Vitamin B-6 for 30 days is the most effective treatment that we know of for tuberculosis.  The fish should be quarantined during treatment time.  Liquid baby vitamins found at your local pharmacy are a good source of vitamin B-6.  One drop per every 5 gallons of aquarium water is sufficient.   Replace the vitamins according to how much water is changed in the tank during treatment time.

Overcrowding and poor water quality are usually the cause of this disease.

Be careful, this disease may spread to humans.


Best Regards,

Dr. Gary Aukes; Pharm D, Dr. Brian Aukes; PhD., and the staff of National Fish Pharmaceuticals.

Fish Articles

Items that can be used to treat the diseases listed in this article include:

Kanamycin Sulfate



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