Bacterial Septicaemia
Aeromonas / Pseudomonas (systemic)
Critical severity
a dangerous internal bacterial infection showing as red streaks, ulcers and bloating, needing fast antibacterial treatment
Symptoms
Spotting illness early gives the best chance of a cure, so check your fish daily at feeding time. Red streaks or blotches in the fins and body, ulcers, bloating, bulging eyes, and rapid decline. A serious internal bacterial infection. If you see several of these signs together, act promptly rather than waiting.
Causes
Systemic gram-negative bacteria taking hold in fish weakened by poor water quality, injury or stress. It spreads through the bloodstream. In nearly every case the underlying trigger is stress, poor water quality, or the introduction of an infected fish - all of which weaken a fish's natural defences.
Treatment
Treat quickly with a broad-spectrum antibacterial (medicated food is best for internal infection), and dramatically improve water quality. Prognosis is guarded once advanced.
While treating, increase aeration, remove activated carbon from the filter (it absorbs medication), finish the full course even after the fish looks better, and keep the water immaculate with regular changes. Always dose for the tank's true water volume and follow the product instructions.
Prevention
Keep water pristine, avoid injury and overcrowding, quarantine new fish, and feed a balanced diet to support immunity. The golden rules are simple: quarantine every new fish for 2-4 weeks, never overstock or overfeed, avoid sudden temperature or chemistry swings, and do regular partial water changes. A stable, clean, low-stress aquarium prevents the large majority of disease.
FAQ
What is Bacterial Septicaemia in fish?
How serious is Bacterial Septicaemia?
What causes Bacterial Septicaemia?
How do I treat Bacterial Septicaemia?
Can Bacterial Septicaemia be prevented?
Will my other fish catch Bacterial Septicaemia?
This information is general guidance, not veterinary advice. Consult an aquatic vet for serious cases.