Re: [RML] mycobacteriosis messages

H. Hoekstra (hugo at
Sun, 06 Jun 1999 01:12:37 +0100

Hello all,

In addition to the recent mycobacteriosis messages I included some messages
that were on the catfish mailinglist this weekend. A (possible) cure is
mentioned and I thought you might be interested to read this. Ofcourse I
would be interested to hear any comments.

Best regards,

Hugo Hoekstra


Mycobacterium will mask itself by a long persistent bout of a bacterial infection or other opportunistic diseases. This is very difficult to diagnose even with good necropsy techniques. There is also a vitamin deficiency that looks a lot like Mycobacterium under the microscope and that can fool even an experienced diagnostician. If you have access to a lab I highly recommend you have your worst infected fish necropsied (it can't be done on a dead fish). If it is Mycobacterium, by the time they get to the stage near death they are way too far gone. Often MB nodules develop on the internal organs, causing permanent damage, long before (weeks and even months) you see the outward symptoms.

Now for the good news. Unlike popular opinion MB is treatable. It is just costly, time consuming, and plenty of work. The treatment is as follows. Kanamycin powder at 1/4 teaspoon per 20 gallons and Isoniazid at one tablet per 10 gallons. You need to do a water change (25% minimum) every 3 days (important) and replace the amount of antibiotic removed. So if you did a 50% water change you add back a 50% dose. This regimen takes between 20-50 days. You can purchase the drugs at the Fishy Farmacy ( You can also consult with Dr. Aukes (one of the worlds leading aquarium fish disease specialists) for a more knowledgeable opinion than mine. Without necropsy or other similar diagnostics, you will never be sure.

I wish you the best and sincerely hope it is not MB. If you have other tanks I would certainly be EXTREMELY careful about sharing any equipment between tanks. It is easy to transmit and can become airborne. MB can be transmitted to humans as well. Be sure you have extra safe handling techniques. Wash with a antibacterial soap after every time your hands go in the tank. Gloves would be preferred (they are real hard to find, good one's that is).

I hope this helps. Feel free to email me with questions. Leon Milberg leon at



> This ounds like a bacterial infection that My tanks > somehow acquired a few years ago. I never found > anything that would help. After most of the corys > died, it cleared up.Many large water changes were the > most helpful. Isolate it because it spreads like > wildfire. About a year later, the same thing > happened. No changes in the tank for about 6 weeks > prior. Again, nothing seemed to help. It cleared up > after many large water changes and has not been back. > GOOD LUCK. Les

Do some research on Mycobacterium. It is a TB like bacteria that is extremely difficult to cure. It does have a cure though. MB has all the appearance of being a low grade bacterial infection. It persists for a long period of time without symptoms. When symptoms do become obvious the fish is long gone. Eventually it will affect all the fish. Many fish have enough of a immune system to ward of the bacteria for quite some time, so it will appear that not all fish have the disease. The bacteria is encased in a hard to penetrate covering, therefore it is quite resistant to nearly all antibiotics. It takes a combination of drugs over an extended period of time. It is the same class of bacteria as tuberculosis. In humans it takes over a year to fully eradicate. In fish it takes 20-50 days. I have found that guppies are highly susceptible to the disease, especially one's kept in very soft water. It will eventually manifest the symptoms through a bent spine.

Large and frequent water changes can keep the unaffected fish from getting the disease. It allows the normal immune system to fight the disease. Since it is prevalent everywhere it usually strikes fish with a stressed immune system.

As I posted already it can be transmitted to humans and usually shows as nodules and skin lesions. Since the disease can go airborne it is highly contagious.

The disease is another opportunistic disease. It can be found everywhere including just plain old dirt from outside. Another way the disease is transmitted is through eating an infected fish. It is usually found in poor water quality BUT NOT ALWAYS.

I had an outbreak that was diagnosed through necropsy. I have a theory on how it got to some fish and not others. It first infected guppies in the tank. The bacterial infection appeared low grade. I saw some fin rot in just a few fish as well as the bent spine in a couple of guppies (this persisted for a couple of months). I did treat them in the tank without isolating them. I did have over a period of a couple of months a death or two of guppies. None of the other fish appeared to have the problem. After a couple of months after that, I saw problems with 5 (of 7) dominant clown loaches that were several years old. This were clearly the largest and most dominant of the group. They had what looked like ich or velvet on their scales. The delta fish in the shoal were not infected. At that point I became panicky and tried every possible cure for bacterial, ich, and velvet, to no avail. That is when I sent a fish out to look at under the scope. I believe the dominant clown loaches, and a few cory's ate an infected fish (I also had a couple Cory losses). After diagnosis I had to euthanize a number of fish before it got to my very expensive fish. Once they started dieing it was all over for many of the fish.

At that point with a clear diagnosis, I contacted Dr. Gary Aukes one of the leading aquarium fish disease experts. He gave me a protocol for treating, which I did. I treated for 40 days and sent a fish (the worst shape one) out for necropsy. All were fine.

This all occurred in a tank that had it's water changed sometimes twice weekly and NEVER longer than once a week. With each water change I vacuumed. I would say I had a fastidious tank care, yet the disease persisted.

The disease is difficult to diagnose as the symptoms can appear just like other diseases. It can also be mimicked by a vitamin (vitamin E) deficiency. There is a professor at the University in Florida that specializes in the distinction of the two disease (Dr Ruth Francis Floyd). She will necropsy a fish but it must be sent to her live. I strongly believe that this bacteria is so common and many suffers losses without an accurate diagnosis.

It is a devastating disease. It scared me half to death as I have a tank with over $1,000 in fish that are clearly pets for me like someone would feel about a dog or cat.

Leon Milberg leon at