Fish & shrimp health guide
Velvet (Gold Dust Disease)
Also called oodinium, rust disease, gold dust
A fine gold or rust-coloured dusting over the skin, best seen with a torch held at an angle.
TL;DR, Velvet (Gold Dust Disease)
Velvet is a parasite like ich but finer and more dangerous. Instead of salt grains it lays a fine gold or rust dust over the skin, easiest to see with a torch shone at an angle in a dim room. Fish clamp their fins, go off food, and breathe hard because it attacks the gills early. It moves fast and kills faster than ich, so treat at the first sign. Labyrinth fish like bettas and gouramis and small fish like killifish are hit hardest.
What you see
A fine yellow-gold to rusty sheen over the body, like the fish has been dusted with powder. Clamped fins, rapid gill movement, flicking, loss of appetite, and lethargy. It often hits the gills first, so laboured breathing can come before the dust is obvious.
What causes it
- A new fish or plant introduced without quarantine carrying the parasite
- Stress and poor water lowering resistance
- A tank that has run warm and bright, which the parasite favours
How to treat it
- Dim the tank and darken it for the course, since the parasite relies on light to feed.
- Raise the temperature slightly if the fish tolerate it to speed its cycle.
- Treat with a velvet-specific medication promptly, this one does not wait.
- Increase aeration, because gill damage plus warm water starves the fish of oxygen.
- Complete the full course past the last visible sign.
Treatment safety in a planted tank
Velvet treatments are often copper-based and lethal to shrimp and snails, and harsh on scaleless fish. Treat in a quarantine tank wherever possible; if you must dose the display, use an invert-safe formula and accept it may be less effective.
Prevent it
Quarantine everything that goes in the tank, fish and plants, and keep stress low. Velvet almost always arrives on an unquarantined newcomer.
Easy to confuse with
Ich makes distinct salt grains, velvet makes a fine even dust. The gold sheen is subtle, so a torch at an angle in a dark room is the reliable way to tell them apart.
Species most at risk
Species that catch this most often, or that need a gentler treatment:
- Siamese Fighting Fish — Labyrinth fish are highly susceptible and often the first to show it.
- Honey Gourami — Small labyrinth fish hit hard and fast by velvet.
- Clown Killifish — Small killifish are very vulnerable, treat at the first dusty sheen.
- Endler's Livebearer — Small, active fish that decline quickly once the gills are affected.
Frequently asked questions
Direct answers to the questions search engines and AI assistants surface most often about this species.
How is velvet different from ich?
Velvet is a fine gold or rust dust, ich is distinct white salt grains. Velvet is smaller, harder to see, attacks the gills early, and kills faster.
Why should I darken the tank?
The velvet parasite photosynthesises to feed, so cutting the light weakens it and helps the treatment work.
How fast do I need to act?
Immediately. Velvet can wipe out a tank in days, much faster than ich, because it damages the gills early.