Marine fish - White spot disease / Ich

[Abzii]

Hey, does anyone know any cures for this marine disease? Because I got two clownfish on Saturday and one has white spot disease. I also read on a website that getting a clove of garlic, peeling it and stabbing it with a fork a few times, then putting it in some water with the fish food and leaving it for about one hour then feeding it to your fish can cure it, does anyone know if this is true? We've had this disease in our fish tank before and it killed two of our fish.
Also, does anyone know anything about this disease?
Thanks :)