Mycobacteriosis

For Mycobacteriosis, stabilise oxygenation and water quality, document signs and isolate only when safe for the host. Do not start medication blindly.

Fish mycobacteriosis pathobiology

Fish mycobacteriosis, colloquially “fish TB”, is an insidious, chronic and often difficult-to-treat bacterial infection, caused predominantly by the acid-fast mycobacterium Mycobacterium marinum. It may present as a chronic or acute systemic granulomatous disease in aquarium fish. These organisms have lipid-rich cell walls containing mycolic acids, which contribute to resistance to disinfectants, environmental degradation and broad-spectrum antibiotics. The bacterium replicates within macrophages and can form caseous granulomas in visceral organs. CRITICAL ZOONOTIC WARNING: M. marinum is zoonotic and may cause aquarium granuloma in people. Wear gloves when handling fish, water or contaminated equipment and seek medical advice for persistent skin lesions after exposure.

Clinical manifestations

• Progressive emaciation (cachexia): severe wasting despite apparently normal feeding.
• Skeletal deformities: lordosis or scoliosis may result from neuromuscular granulomas.
• Skin ulceration: deep, non-healing hemorrhagic ulcers may occur.
• Exophthalmos: protruding eyes can reflect mass effect from retrobulbar granulomas. Signs are variable and nonspecific and can also include ascites, paleness, loss of equilibrium, reduced activity and loss of appetite.

Main differentials: chronic bacterial disease, neoplasia, starvation and internal parasites. Priority changes with host, site and progression.

Transmission and pathogenesis

1. Cannibalism and necrophagy: ingestion of dead, infected tank mates is an important route for rapid transmission.
2. Biofilm and substrate reservoirs: bacteria thrive in detritus-rich environments and anaerobic pockets within the substrate.
3. Immunocompromise: chronic stress from suboptimal parameters facilitates initial macrophage colonisation.

Transmission and pathogenesis

1. Cannibalism and necrophagy: ingestion of dead, infected tank mates is an important route for rapid transmission.
2. Biofilm and substrate reservoirs: bacteria thrive in detritus-rich environments and anaerobic pockets within the substrate.
3. Immunocompromise: chronic stress from suboptimal parameters facilitates initial macrophage colonisation.

Confirm clinically and sample before antimicrobials; cytology, culture and susceptibility or molecular methods require professional interpretation.

For Mycobacteriosis, stabilise oxygenation and water quality, document signs and isolate only when safe for the host. Do not start medication blindly.

Documented options to verify for Mycobacteriosis: immediate environmental support and any medicine only through an evidence-based recommendation, official label and host assessment.

Seek veterinary help for Mycobacteriosis with respiratory distress, hemorrhage, loss of balance, failure to feed, rapid progression or mortality.

Prevent Mycobacteriosis with proportionate quarantine, separate tools, daily observation and stable parameters; avoid routine drug prophylaxis without an indication.

Seek veterinary help for Mycobacteriosis with respiratory distress, hemorrhage, loss of balance, failure to feed, rapid progression or mortality.