do a lot of research into how many stores have come and gone. Two of the most predominant common denominators have been low/no profile locations, and catering to coral collectors. The thin margins, and large start-up costs/high on-going overhead, cannot be sustained by such a small demographic.
Now look at the two stores that have been around the longest, aquarium arts and aquatouch. Both are located just off the access of a major freeway (easy access), and both, are in a typical strip mall (high visibility).
Although a lot of the members on this forum go to these stores, the primary demographic that keeps these stores going, will never be members on this forum, or any other forum. Meaning, your concern should be, "how do i inspire the typical american family that this is a hobby they will love, and do i offer everything they would need to come in, be inspired, and leave a few thousand dollars lighter, but totally excited about their new adventure!"