Hex fish tanks offer 2 more angles than basic rectangular tanks for viewing fish. Of course, for some people, this is not necessarily a positive. Some people, quite reasonably, prefer to view their aquarium life from a large plane, from the front of a basic, rectangular-shaped tank from which more can be seen at once.
But the 90 degree angles where the four sides of these rectangular tanks come together can obstruct the view a bit. Hex fish tanks, on the other hand, have only 60 degree angles at the seams between sides (and acrylic tanks often have no seams at all). This gives a good viewing vantage point.
One of the most popular places to put hex fish tanks is in a corner. Of course, newer corner-shaped tanks are also becoming popular for corners. Your choice may depend greatly upon your personal tastes and the overall décor you want to display. The hexagon-shape of hex fish tanks is interesting, regardless of what you have inside it. And when you add the beautiful underwater environment within it, the effect can be breath-taking.