Treatment Protocol for Fish Tuberculosis (Mycobacterium)
Fish TB is extremely difficult to treat and often incurable. Euthanasia is often the most humane option for severely affected fish. Minocycline or kanamycin may help mild cases. IMPORTANT: Mycobacterium marinum can infect humans through open wounds — always wear gloves when handling infected tanks.
How to Identify This Condition
Look for these symptoms in your fish:
- Chronic weight loss despite eating
- Curved spine (scoliosis)
- Skin ulcers and lesions
- Fin deterioration
- Lethargy and hiding
- Pale coloration
Early detection is critical — the sooner you begin treatment, the better the prognosis. Observe your fish daily during routine feeding for any behavioral or physical changes.
Root Causes
Understanding what caused the problem helps you prevent recurrence:
- Mycobacterium marinum bacteria
- Eating infected dead fish
- Contaminated water or equipment
- Chronic stress weakening immunity
Recommended Medications
The following medications are effective against Fish Tuberculosis (Mycobacterium):
- Minocycline — follow manufacturer dosing instructions. Treat in a hospital/quarantine tank when possible to avoid disrupting your main tank's biological filtration.
- Kanamycin — follow manufacturer dosing instructions. Treat in a hospital/quarantine tank when possible to avoid disrupting your main tank's biological filtration.
- Rifampin (rarely effective) — follow manufacturer dosing instructions. Treat in a hospital/quarantine tank when possible to avoid disrupting your main tank's biological filtration.
Always have these medications on hand before you need them. See our quarantine tank guide for proper treatment setup.
Water Quality During Treatment
Maintain pristine water conditions during treatment. Perform 25% daily water changes using Seachem Prime as your water conditioner. Remove activated carbon from your filter during medication (carbon absorbs medications). Increase aeration with an air stone — sick fish need extra oxygen. Monitor ammonia and nitrite daily with your test kit.
Recovery & Quarantine
This is a critical-severity condition. Prognosis depends heavily on how quickly treatment begins. Isolate affected fish immediately in a hospital tank. Continue treatment for the full 42-day protocol even if symptoms improve — stopping early risks relapse. Monitor the main tank for additional cases.
Prevention
The best treatment is prevention. Follow these practices to reduce the risk:
- Remove dead fish immediately
- Quarantine new fish
- Maintain excellent water quality
- Never share equipment between tanks without disinfecting
- Wear gloves if you have cuts on hands
For a complete prevention strategy, read our quarantine tank guide and maintenance schedule.