Exactly, taufiq85! The water has to have zero copper and the original water used to make salt mix must be pure (RO/DI) water. Frozen food is accepted, but they must be trained to eat them first. Cuttlefish require the same water parameters as coral, but they must be kept alone and fed food everyday. Crustaceans only, fish are not recommended. They are perceived as harder to keep mainly because of their diet. If you have a constant source of food, a large tank with plenty of hiding spots, and a protein skimmer and filter to deal with bio loads three times the average fish, then by all means, go ahead! It will be interesting if you keep one, Marine Life Aquarium sells them, and if you do have one, remember to post pics!
Cheers!