Causative agent: Mycobacterium marinum / M. fortuitum / M. chelonae — slow-growing mycobacteria
Fish Tuberculosis, caused by Mycobacterium marinum and related species, is one of the most serious and misunderstood diseases in the Australian aquarium hobby. Because it is a slow-progressing wasting disease, it is frequently misdiagnosed as malnutrition, parasitic infection, or simply old age — by the time a fish's spine visibly curves and its belly becomes hollow, the disease has often been present for months or even years. There is no effective cure available to hobbyists. Once fish tuberculosis is confirmed or strongly suspected in a tank, affected fish should be humanely euthanised and the aquarium thoroughly disinfected. Critically, Mycobacterium marinum is a ZOONOTIC pathogen — it can infect humans through breaks in the skin during tank maintenance, causing a chronic skin condition known as "fish handler's disease" or "aquarium granuloma." Australian hobbyists who develop persistent skin sores on their hands or arms after aquarium contact should consult a doctor and mention their fishkeeping hobby.
Symptoms
- •Progressive weight loss and wasting
- •lethargy
- •colour loss
- •curved or bent spine
- •skin ulcers
- •fin rot
- •dropsy
- •popeye
- •hollow belly
- •may mimic many other diseases
Treatment
- •No effective cure available to hobbyists
- •euthanise affected fish
- •disinfect tank with bleach
- •UV steriliser may reduce spread
- •supportive care only
Australian Medications
- •No specific treatment available in Australia
Commonly Affected Fish
- •All freshwater and marine fish
- •bettas, gouramis, cichlids, and livebearers frequently affected
Important Notes
ZOONOTIC — wears gloves when handling tank water if TB is suspected. Can cause chronic skin granulomas in humans. No cure — euthanise affected fish.