I wouldn't get a hex either unless it's a really big hex and it's going to be viewed on all six sides. You will be quite limited to what fish you can have in a hex because of the smaller surface area. Having a large surface area is not only good for oxygen transfer but it's also the swimming area of your fishes. Most fish as far as I know likes to swim more horizontally than vertically so having a longer and wider tank is more benificial than having a taller tank like a hex. Basically you're fish would be swimming in circles in a hex and it won't have enough room to swim in either directions to get away from a territorial tankmate. And if you're maximixing space in your house a hex is definetly not the way to go unless you have a hexagonal indentation on your wall.