Velvet (Oodinium)
Caused by a dinoflagellate parasite. Appears as a fine gold or rust dust on the fish. Highly contagious and fast-moving, often fatal if not treated immediately.
Check these symptoms in your tankSymptoms of Velvet (Oodinium)
- Gold/rust-colored dust on skin
- Scratching against objects (flashing)
- Rapid gill movement / labored breathing
- Fins clamped against body
- Lethargic / hiding more than usual
- Faded or lost color
How to treat Velvet (Oodinium)
- Turn off aquarium lights (parasite is photosynthetic)
- Copper medication (Copper Power), most effective
- Freshwater: chloroquine phosphate or formalin-based treatments
- Increase aeration, velvet reduces gill efficiency
- Hospital tank strongly recommended
How to prevent it
- Strict 4-week quarantine for all new fish
- Maintain high water quality, stressed fish are more susceptible
Conditions with similar symptoms
The most common aquarium disease. Caused by the parasite Ichthyophthirius multifiliis. Looks like salt grains on the fish's body and fins.
Saltwater equivalent of freshwater ich. Caused by Cryptocaryon irritans. More difficult to treat than freshwater ich.
Includes skin and gill flukes, anchor worms, and fish lice (Argulus). Fish may scratch against objects (flashing) and produce excess mucus. Often introduced with new fish or live food.
Not sure? Use the symptom checker
Many fish diseases look alike. Pick the symptoms you see in the free fish disease checker to compare likely causes, or scan a test strip to rule out a water problem first.