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What Is Chronic Wasting Syndrome?

by Shari Sanford last modified Feb 09, 2008 11:52 AM
Not really a "disease."

There are a variety of causes for wasting in fish.




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.


    myxobolus -

...check the bookmarks for the list...

Combinations of both

Sometimes stunting can be confused with early stage CWS. Fish doesn't grow. don't know the conditions of all fish before getting to your tank. Difficult to determine if a fish is actually stunted or simply failing to thrive for other reasons.

Is it contagious?

    Not necessarily, though because it is a chronic illness and the symptoms are slow to appear, it can be. I have seen fish with skinny in a tank full of fish where they are the lone ill fish and the others are all fat and sassy (see the pic of the Syncrossus with the Modestas). I have also seen a tank full of fish that all seem to have it to one degree or another. It's also possible for one fish to have it, be removed for treatment, cured, placed back into the main tank and then other fish succumb to it. (been there, done that and ended up treating the whole tank) It all depends on what exactly is causing your fish to waste away. If it's parasitic, treating the whole tank is needed. If it's bacterial, you should also treat the whole tank. Likewise if it's a combination of the two. The trick is knowing what it is that causes this. Which is the problem.

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