Emergency Guide — What to Do When Your Fish is Sick

A sick fish is stressful. You panic. You want to do something immediately. But the wrong action can make things dramatically worse. Follow this protocol in order — it covers 95% of fish emergencies.

Step 1: Observe — don't react yet

Before you do anything, spend 5 minutes observing the fish. Is it one fish or multiple? What are the symptoms exactly: white spots, torn fins, bloating, gasping at surface, lying at bottom, color changes, loss of appetite? Is the fish swimming normally or struggling? The symptoms tell you what's wrong. Treating blindly with medication often makes things worse.

Step 2: Test your water immediately

90% of fish emergencies are caused by water quality. Test ammonia, nitrite, nitrate, and pH right now. Ammonia above 0.5ppm or nitrite above 0ppm is an emergency. Do an immediate 30-50% water change with dechlorinated water at the same temperature. Add Seachem Prime to detoxify remaining ammonia. Retest in 2 hours.

Step 3: Identify the disease

White spots (salt/sugar-like): ich. Treat with heat method or ParaGuard. White cottony patches: fungal infection. Treat with API Fungus Cure. Red streaks or ulcers: bacterial infection. Treat with Seachem KanaPlex. Pinecone scales (fish looks like a pine cone): dropsy — often fatal, quarantine immediately. Torn fins with white edges: fin rot — improve water quality first, then treat. Bloated belly, floating sideways: swim bladder — often from overfeeding, fast the fish 48 hours.

Step 4: Quarantine the sick fish

Move the sick fish to a quarantine tank (QT) before medicating. This protects healthy fish, allows precise medication dosing, and prevents medication from killing beneficial bacteria in your main tank. Your QT should have a cycled sponge filter, heater, and a simple hide. Remove activated carbon from the filter — it absorbs medication.

Step 5: Support recovery

During and after treatment: keep water pristine (small daily water changes in QT), maintain stable temperature, feed lightly with high-quality food, add Seachem Stress Guard to reduce stress and protect the slime coat. Most diseases are survivable with prompt, correct treatment. The fishkeepers who lose fish are the ones who wait too long.