Troubleshooter

Why is my fish gasping at the surface?

Quick answerGasping = oxygen crisis. Causes: ammonia spike, dirty filter, overcrowding, high temperature, gill parasites. Test water immediately and increase surface agitation.

Possible causes (5)

1. Ammonia poisoning

Damages gills, fish can't extract oxygen. URGENT: test ammonia, do a 50% water change, dose Seachem Prime.

2. Low dissolved oxygen

Hot water + still surface + overstocking. Add a powerhead or air stone for surface agitation.

3. Gill flukes or velvet

Gill parasites destroy oxygen exchange. Treat with PraziPro (flukes) or copper (velvet) in QT.

4. CO2 toxicity (planted tanks)

Excess CO2 from injection drops dissolved oxygen. Lower BPS + increase surface agitation.

5. High temperature

Above 84°F drops oxygen capacity. Cool the tank.

What to do next

Test water first - many "behavior" issues are actually water-quality problems. Use the water parameter checker to score your test results, the disease symptom matcher if you observe physical signs, or the general diagnoser to narrow further. Browse the full disease database if illness is suspected.

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