FISH DISEASE ARTICLES: MYCOBACTERIOSIS
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.
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
Be careful, this disease may spread to humans.
Dr. Gary Aukes; Pharm D, Dr. Brian Aukes; PhD., and the staff of National Fish