Causative agent: Aeromonas hydrophila, Pseudomonas fluorescens, or Vibrio spp.; sometimes Saprolegnia (fungal) as secondary infection
Fin rot is among the most frequently encountered diseases in Australian aquariums and is almost always the result of poor water conditions, overcrowding, or stress weakening a fish's immune defences. The ragged, fraying appearance of the fins — which may progress from milky white edges inward to the fin base — is caused by bacterial infection from Aeromonas or Pseudomonas species, which are ever-present in aquarium water but only cause harm in stressed or immunocompromised fish. Bettas are especially prone due to their elaborate finnage, and guppies and goldfish are also commonly affected in Australian home aquariums. Caught early, fin rot is one of the most treatable aquarium diseases: a thorough water change, improved filtration, and a course of Aristopet Aquaricycline or Aquasonic Bio-Tet will resolve most cases. In severe cases where the rot has reached the fin base, the fish may not fully recover its original finnage, but survival is still achievable with prompt treatment.
Symptoms
- •Ragged, frayed fins
- •discolouration of fin edges (white, brown, or black)
- •fin tissue dissolving
- •redness at base of fins
- •lethargy
- •clamped fins
Treatment
- •Antibiotics (erythromycin, tetracycline)
- •antifungal if fungal component present
- •aquarium salt
- •improve water quality
- •trim dead fin tissue in severe cases
Australian Medications
- •Aristopet Aquaricycline
- •Aquasonic Bio-Tet
- •Aristopet Fin & Body Cure
- •Aquasonic Bactonex
Commonly Affected Fish
- •All freshwater and some marine fish
- •bettas, goldfish, guppies most commonly affected
Important Notes
Early detection is key — fin tissue does not always fully regrow once damage reaches the fin base.