Fish Tuberculosis (Fish TB)

Not to be confused with the human disease, it’s common in tropical fish tanks. It’s possible that it could go unnoticed, as the disease is not highly contagious and has no sudden dramatic effects.

Like the human version, it may not show signs until years after infection begins.


Physical Signs

  • Your fish may become lethargic
  • Hollowed belly
  • Turn pale
  • Skin ulcers
  • Frayed fins
  • Fin and scale loss
  • Yellowish or darker nodules may appear on the eyes or body


Behavioral Signs

  • Loss of appetite
  • Refusing to eat
  • Hiding behavior


Potential Causes

Fish TB is caused by one of the several species of Mycobacteria:

M. fortuitum, M. flavescens, M. chelonae, M. gordonae, M. terrae, M. triviale, M. diernhoferi, M. celatum, M. kansasii, M. intracellulare, and M. marinum.

And the main cause for this disease is a poorly maintained aquarium. Mycobacterium thrives in low pH values, low oxygen, high soluble zinc, fulvic and humic acids.

All the problems you’ll encounter if you’ve overstocked or can’t be arsed to maintain your tank.

Possible Treatments

There is no current vaccine or satisfactory treatment available. Once a population of fish is infected, the most likely scenario is euthanasia, followed by disinfecting your tank. It makes little sense to attempt to maintain a population with the illness.

They’ll have chronic health problems, poor growth, and feed conversion rates. Infected fish will be a constant source of infection.

Note: If you suspect your tank is infected with Fish TB, you should take precautions. Although it’s very unlikely, it’s possible for humans to contract this disease from fish.

If you have ANY cuts, scratches, or lesions etc. on your hands don’t put them in the tank.

If you need to put your hands in the tank, wear rubber gloves and keep sterilizing gel close by. And don’t use anything from the aquarium on anything else in your house.