How to Treat Dropsy in Aquarium Fish: A Complete Guide

How to Treat Dropsy in Aquarium Fish: A Complete Guide


How to Treat Dropsy in Aquarium Fish: A Complete Guide

Dropsy is one of the most alarming conditions aquarium fish can develop. It’s not actually a disease itself but a symptom of an underlying issue, often related to internal infections, poor water quality, or organ failure. If you've noticed a fish with a bloated belly, raised scales (like a pinecone), and lethargy, you're likely dealing with dropsy.

Early diagnosis and quick action are key. In this guide, we’ll walk you through everything you need to know to identify, treat, and hopefully save your fish from dropsy.

What Is Dropsy?

Dropsy is a condition where a fish’s body swells due to fluid buildup in the tissues and body cavity. It’s often the result of:

  • Kidney or organ failure

  • Bacterial infection (commonly Aeromonas)

  • Poor water quality or stress

  • Weakened immune system

It’s more common in freshwater fish like bettas, goldfish, and tetras, and often occurs in tanks with poor water conditions or overcrowding.

Symptoms of Dropsy

Here are the key signs to look for:

  • Swollen, bloated body

  • Pinecone appearance (raised scales)

  • Bulging eyes

  • Loss of appetite

  • Lethargy and isolation

  • Clamped fins

  • Redness or ulcers

If you notice any of these symptoms, act quickly—dropsy can progress fast and is often fatal if untreated.

Step-by-Step Treatment for Dropsy

Step 1: Quarantine the Sick Fish

Immediately move the affected fish to a hospital tank to prevent the condition from spreading and to reduce stress.

  • Use clean, dechlorinated water

  • Keep water temperature stable

  • Add an air stone for good oxygenation

Step 2: Improve Water Quality

Check your main tank for ammonia, nitrite, nitrate, and pH levels. Dropsy is often linked to poor water conditions, so do the following:

  • Perform a 25–50% water change

  • Clean the filter (don’t kill beneficial bacteria!)

  • Vacuum debris from the substrate

Step 3: Use Aquarium Salt

Add aquarium salt to the hospital tank—this helps reduce fluid buildup and stress.

  • Dosage: 1 tablespoon per 5 gallons

  • Dissolve salt before adding it to the tank

Step 4: Administer Antibiotics

Use a broad-spectrum antibiotic like Kanamycin or Maracyn Two. These target internal bacterial infections effectively.

  • Follow dosing instructions carefully

  • Treat for at least 5–7 days

  • Monitor your fish closely

Step 5: Feed High-Quality, Medicated Food (Optional)

If your fish is still eating, try feeding medicated antibacterial food. Otherwise, rely on water-based treatments.

Prevention Tips

Prevention is always better than cure. Here’s how to reduce the risk of dropsy:

  • Keep water clean – Regular water changes are essential

  • Avoid overfeeding – Uneaten food can rot and affect water quality

  • Use a good filter – Maintain biological filtration

  • Don’t overcrowd your tank

  • Quarantine new fish – Prevent introducing disease

Final Thoughts

Dropsy is a serious condition that requires fast action and attentive care. While not all fish recover, starting treatment early gives your fish the best chance. Keeping your tank clean, stable, and stress-free is the best defense against this and other health issues.

Got a fish that looks unwell? Don’t wait—test your water, set up a hospital tank, and take action. Your fish will thank you for it.


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