From my site:
May also be known as Rust, or Gold Dust. The symptoms and lifecycle of velvet is similar to ich.
Signs: Like ich, it can be found in small traces in the healthiest of tanks. But it will attack any unhealthy, or stressed fish. You may not be able to see velvet easily, unlike ich. Shine some light on the fish, and even use a magnifying glass to see the gold dust on your fish. Advance stages their skin begins to peel.
Take action immediately. Sometimes this is not diagnosed before the fish is in the advanced stage. Once detected, immediately raise the temperature (about 82-84 F), Take out your carbon filter cartridge, dim the lights, begin using Aquarium Salt, and treat with Copper Sulphate for ten days. Jungle also makes velvet medication. Instructions should be on the back of the item."