When its time to start buying marine fish you are going to need to find a good aquarium store. You should visit several stores before making a decision on which one you will do your business with. Things you should take into consideration is how educated the staff is. Are they helpful and answer your questions or at least able to give you a idea where you can get the answer? Look the store over for cleanliness, a clean store has a better chance of selling healthy disease free fish than a store that is a mess and smells bad. You want to make sure the store sells everything you need weather its aquarium supplies or fish.  A good marine fish store will have a quarantine tank to keep sick fish away from the others do keep the other fish from being exposed to disease. A store without a quarantine tank could be a indication that they do not have a problem with you buying marine fish that are sick or diseased.