Fin rot is a bacterial infection (typically Aeromonas, Pseudomonas, or Vibrio) that causes ragged, eroded, or discolored fins. Common opportunistic infection triggered by poor water quality or wounds.
Poor water quality (high ammonia/nitrite/nitrate), aggressive tankmate damage, fin nipping, or rough handling during shipping.
Multiple effective treatments exist. Pick based on your tank type, livestock sensitivity, and severity. Always treat in a separate quarantine/hospital tank - most medications are toxic to coral, invertebrates, and live rock biology.
Maintain perfect water (0 ammonia, 0 nitrite, <20 nitrate). Remove aggressive tankmates. Avoid fin-nippers like tiger barbs in community tanks.
Ragged or torn fin edges. White or black edges on fins. Fins shortening over days.
Poor water quality (high ammonia/nitrite/nitrate), aggressive tankmate damage, fin nipping, or rough handling during shipping.
Water change + clean conditions: For mild cases: 50% water change, perfect water parameters, no further treatment needed. Fins regrow in 2-4 weeks.
Maintain perfect water (0 ammonia, 0 nitrite, <20 nitrate). Remove aggressive tankmates. Avoid fin-nippers like tiger barbs in community tanks.
Mild to moderate - usually treatable
Always treat in a separate quarantine or hospital tank. Most medications are toxic to coral, invertebrates, and live rock biology.
Browse the full disease database for 45 aquarium conditions with treatment protocols, or check the care library for prevention-focused husbandry guides. Use our symptom matcher to rank likely diseases from observed signs, the water parameter checker to diagnose related water-quality issues, or the QT timeline calculator to plan a treatment schedule.