oh srry no it dosn't have to be square or retangle those are just what are traditional. if you have any thing left over you should try a mini trangle tank.
I tried talking my girl into turning one of the spare bedrooms into a tank and then just being able to view it from the outside windows lol.
but I was just kidding... right?
true... but atleast she compromised... I'm putting a 7'x7' in it... pretty much takes up the whole room haha... just leaves space to walk around and for our computer desk.