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Fish disease symptom checker

Pick the symptoms you can see. You get the likely causes and what to do next. Many fish problems start in the water, so scan a test strip too.

Educational use only. This checker is not veterinary advice and cannot diagnose fish with certainty. If animals are in distress, consult an aquatic veterinarian or qualified fish health professional.

Appearance

White spots on body/fins

Gold/rust-colored dust on skin

White cottony patches

Ragged or fraying fins

Discolored fin edges (brown/red)

Swollen/bloated abdomen

Scales sticking out like a pinecone

Bulging or cloudy eye(s)

Open sores or ulcers on body

Faded or lost color

Red streaks or inflammation

Pits or holes on head/lateral line

Excess mucus / slime coat

Behavior

Scratching against objects (flashing)

Rapid gill movement / labored breathing

Gasping at surface

Lethargic / hiding more than usual

Refusing to eat

Swimming sideways or upside down

Spinning or erratic movement

Fins clamped against body

Sitting on bottom abnormally

Select symptoms above to see possible conditions.

Before you treat: three steps

Test your water first

Many fish diseases are caused or worsened by poor water quality. Test ammonia, nitrite, nitrate, and pH before treating.

Quarantine sick fish

Move affected fish to a hospital tank if you can. It limits spread and lets you treat without harming healthy tank mates.

Watch for 24 to 48 hours

Unless symptoms are severe, observe and write down what you see before treating. A wrong diagnosis can make things worse.

Not sure it is the fish? Scan a test strip to check your water, or start a tank log to keep your tests and treatments in one place. No account needed.