I understand that the prices of aquariums can be... very high. But Personally I think that if your able to wait a little longer and save some more money, try to see if you can find someone selling a larger setup maybe in your classified section of your local newspaper or whatever. You can normally buy a second hand setup for a fraction of the price if you purchased it brand new. RB Piranhas are only really "impressive" in a group of 3 - 5, in which case you should be aiming at a 75 - 100 Gallon tank. Piranhas are a special fish which will earn you many compliments if you do it setup correctly. So make sure that your serious about wanting to own one / a few and do it right, it's a larger investment, but you'll be happier in the long run.