FishTankFish symptom checker: what's wrong with my fish?
Tick what you see, and this free checker lists the most likely causes, how urgent each one is, and the first steps to take. It covers the 14 problems I see most often in freshwater tanks.
What does the fish look like or do?
Anything else going on?
Tick one or more boxes to see the likely causes.
This is a starting point, not a diagnosis. Fish show the same signs for many problems. If you can, ask a fish vet or an experienced local fish store, and treat in a hospital tank when you can.
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Send me the free logQuick answers
| If you see | It is most likely |
|---|---|
| White spots like salt | Ich. Raise the heat slowly and treat the whole tank. |
| Gasping at the surface | Usually ammonia, nitrite or low oxygen. Test the water and add surface movement. |
| Ragged fins | Fin rot or fin nipping. Clean water first. |
| Pinecone scales | Dropsy. Move the fish to a hospital tank. |
| Floating or upside down | Swim bladder trouble, often from overfeeding. Fast for 2–3 days. |
| Cotton tufts | Fungus, or columnaris if the patches are at the mouth or back. |
| Thin but eating | Internal worms. Deworm the whole tank. |
Before you treat anything
- Test the water. Ammonia and nitrite should be 0, nitrate under 40 ppm. Fix the water before you add medicine.
- Check the temperature. A stuck or broken heater causes gasping, clamped fins and ich outbreaks.
- Treat the right volume. Use the dosing calculator to work out the dose for your tank.
- Take out carbon from the filter while you treat, or it soaks up the medicine.
- Watch your shrimp and snails. Copper and many parasite medicines kill them. Move them out first, or check the label.
- Quarantine new fish for 2–4 weeks so the next problem stays out of the main tank. See how to set up a quarantine tank.
A basic fish first aid kit
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- Test kitAPI Freshwater Master Test KitThe first thing to reach for when a fish looks wrong. Tests ammonia, nitrite, nitrate and pH.
- Water conditionerSeachem Prime (500 ml)Binds ammonia and nitrite for a day or two while you do water changes.
- Ich medicineAquarium Solutions Ich-X (16 oz)The ich medicine I keep on the shelf. Treats ich and other external parasites.
- AntibioticSeachem KanaPlexA broad antibiotic for fin rot, columnaris and other bacterial infections.
- DewormerHikari PraziProPraziquantel for flukes and most internal worms. Safe for shrimp and snails.
- Hospital tank5 or 10 gallon tankA small spare tank to treat one fish without dosing the whole display tank.
Related: Water test results tool · Dosing calculator · Why are my fish dying? · Ich · Fin rot