I purchased a 55 gallon acrylic tank about two weeks ago for $50 dollars. I love it. I am, however, saddened by the fact that most fish I adore cannot possibly be expected to live in it at adulthood. I feel that the width is tragically small ringing in at 12 to 13" (roughly). What are some of the fish that CAN successfully live in a 55 gallon that is 4' long? I had my eye on convict cichlids, green terrors, south american puffers, etc. I am still uneasy putting any of these rather small fish in knowing that they'll never fully enjoy the environment. Am i wrong to think I am so limited with options?