Fin Rot in Betta Fish: Complete Treatment Guide

**Quick Answer:** Fin rot in betta fish is a bacterial infection causing deteriorating, frayed fins with discoloured edges. Treat by improving water quality, performing 25-30% daily water changes, and using medications like API Fin & Body Cure or Blue Planet Multi Cure. Most cases improve within 7-14 days with proper treatment.

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What is Fin Rot?

Fin rot is a common bacterial infection that affects betta fish and other aquarium species. It primarily targets the fins and tail, causing them to deteriorate, fray, and disintegrate over time. The condition is usually caused by opportunistic bacteria (typically Pseudomonas, Aeromonas, or Vibrio) that attack fish with compromised immune systems.

If left untreated, fin rot can progress from the edges of the fins toward the body, eventually affecting the body tissue itself (body rot). This advanced stage is much more difficult to treat and can be fatal.

Symptoms

Fins appear frayed, ragged, or torn at the edges

White, grey, or black discolouration along fin edges

Fins look like they're "melting" or disintegrating

Receding fin tissue with visible deterioration

Redness or inflammation at the base of fins

Clamped fins held close to the body

Lethargy and reduced swimming activity

Loss of appetite in advanced cases

Causes

Poor water quality (high ammonia, nitrite, or nitrate levels)

Infrequent water changes or inadequate tank maintenance

Overcrowded tank conditions

Physical injuries from sharp decorations or aggressive tankmates

Stress from improper water parameters or temperature fluctuations

Weakened immune system from poor diet or previous illness

Bacterial bloom in the aquarium water

Treatment Steps

1. **Test water parameters** - Check ammonia, nitrite, nitrate, pH, and temperature

2. **Perform water changes** - Do 25-30% daily water changes with conditioned water

3. **Clean the tank** - Gently vacuum substrate to remove waste and debris

4. **Add medication** - Use API Fin & Body Cure ($16-22 at Aquarium Spare Parts Adelaide) or Blue Planet Multi Cure ($15-20 at Petbarn)

5. **Remove carbon filtration** - Carbon will absorb medication, making it ineffective

6. **Continue treatment** - Follow package instructions, typically 5-7 days

7. **Maintain optimal temperature** - Keep water at 26-28°C to boost immune function

See photos of fin rot at different stages? Upload your fish's picture to FinsDoc for accurate diagnosis: https://finsdoc.com.au

Prevention

Maintain excellent water quality with 0ppm ammonia and nitrite

Perform regular 25-30% weekly water changes

Avoid overcrowding (minimum 20L tank for a single betta)

Feed high-quality foods with variety (pellets, frozen foods, occasional treats)

Inspect tank for sharp decorations that could tear fins

Quarantine new fish for 2-4 weeks before adding to main tank

Monitor tank mates for aggressive behaviour

When to Worry

If fin rot has progressed to the point where it's affecting the body (body rot), or if you notice the deterioration spreading rapidly despite treatment, immediate action is required. Signs that the infection has become severe include: red streaks in the fins or body (indicating blood poisoning), cotton-like growths (secondary fungal infection), or fins that have deteriorated to the base. In these cases, consider using a stronger medication like Seachem KanaPlex ($28-35 at specialist stores) which treats both gram-negative and gram-positive bacterial infections.

Common Questions

**How long does it take for fins to grow back after fin rot?**

With proper treatment and water conditions, betta fins typically begin to show regrowth within 1-2 weeks. Complete regeneration can take 1-3 months depending on the severity of damage. The new growth often appears clear or transparent before developing colour.

**Can fin rot heal on its own?**

Minor cases of fin rot may improve with just water changes and improved conditions. However, most cases require medication to fully eliminate the bacterial infection and prevent recurrence.

**Is fin rot contagious to other fish?**

Fin rot itself isn't directly contagious, but the bacteria causing it can affect other fish with weakened immune systems or injuries. It's best to quarantine affected fish to prevent potential spread.

**How can I tell the difference between fin rot and fin nipping?**

Fin nipping typically shows clean, U-shaped chunks missing from fins, while fin rot presents as deteriorating edges with discolouration. FinsDoc's AI can help distinguish between the two by analyzing photos of your fish.

**Can I use aquarium salt to treat fin rot?**

For mild cases, aquarium salt (1 tablespoon per 19 litres) can help, but it's not effective against more established bacterial infections. Salt should be used cautiously with bettas as they're sensitive to prolonged exposure.

Worried about your betta's fins? Join over 750 Australian fish keepers who trust FinsDoc for accurate diagnosis. Upload a photo now at https://finsdoc.com.au and get personalised treatment recommendations for your betta's specific condition.