Copper is typically used in aquariums to rid fish of Ich, velvet, and other parasites.
Below is a list of the top 2 items I have used to get rid of parasites.
1. Metroplex. This is my first choice since it does not require that you remove the carbon from your filtration system and/or turn of your protein skimmer and/or UV sterilizer. Metroplex may be added to your fishes food and consumed as a medicine. Make sure to allow the Metroplex to sit in your food for at least 30 minutes for it to bind to the fish food. You can also buy Focus to help bind metroplex to the food faster and more effectively.
2. Imagitarium Parasite Remedy is my second choice. This is another good choice to cure ich and other parasites that is not to harsh on your fishes and may also be used in a reef tank. Carbon will need to be removed from your filter along with turning off your protein skimmer and UV sterilizer for maximum effect.