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Along with tank size could you tell us what other kind of fish you have in that tank please? Since your tank has only been set up for a week it is cycling so we need to know what your water readings are (ammonia, Nitrites, Nitrates). Here are some good articles for beginners
http://www.fishlore.com/Forum/freshw...ginners.0.html .
Angelfish and Gouramis usually don't get along very well unless the tank is huge. They are both strongly territorial and will claim a large area. You may need to take one or the other species back to the fish store if the aggression doesn't settle down.
Carol