Causative agent: Vibrio spp., Aeromonas spp., Pseudomonas spp. — gram-negative opportunistic bacteria
Bacterial ulcer disease — also known as haemorrhagic septicaemia or red pest — is a broad category of serious bacterial infection caused by opportunistic gram-negative bacteria such as Aeromonas, Vibrio, and Pseudomonas. These bacteria are naturally present in most aquariums and cause disease only when a fish is stressed or its immune system is compromised. The resulting infections manifest as open, angry-looking ulcers on the skin and muscles, often accompanied by red haemorrhagic streaking and bloody patches visible through the skin. In Australian aquariums, this presentation is most commonly seen following handling injuries, fights, shipping stress, or sudden deterioration in water quality. Antibiotics are essential — in mild cases, Aristopet Aquaricycline or Aquasonic Bio-Tet can be administered via the water, but in serious systemic infections, a veterinary consultation is recommended to obtain injectable or prescription-strength antibiotics. Rapid intervention dramatically improves survival odds.
Symptoms
- •Open sores or ulcers on body
- •haemorrhaging or red streaks in skin
- •bloody patches under skin
- •red fins
- •pop-eye
- •lethargy
- •loss of appetite
- •rapid breathing
Treatment
- •Broad-spectrum antibiotics (kanamycin, tetracycline, chloramphenicol)
- •antibiotic-medicated food
- •wound disinfection
- •hospital tank
- •immediate water quality improvement
Australian Medications
- •Aristopet Aquaricycline
- •Aquasonic Bio-Tet
- •vet-prescribed antibiotics for severe cases
Commonly Affected Fish
- •All marine and freshwater fish
- •most common in stressed or injured fish
Important Notes
Commonly secondary to stress, injury, or poor water quality. Severe cases should be reviewed by an aquatic vet.