Umm, I'd seriously look into consulting a structural engineer for something like that. Say for example your tank weighs 300lbs (at least). Water weighs 8.33lbs per gallon x 300 gallons = 2499 lbs. Add 100lbs of rocks, driftwood, decoration, etc and the whole thing weighs 2899lbs. Lets say the tank is 8' L x 2' W x 2.5' H. 2899lbs on 16 square feet is a LOT of pressure.
If you have the Barron's Piranha book, turn to pg 34 and read it. If not, here is a paragraph from it:
"The floors of many homes are not constructed to support such a massive concentrated weight. It is common for apartment houses to limit the size and weight of aquariums permitted on upper floors. It is best not to place any large aquarium in the middle of a room where it would be located far from supporting architectural structures. Ground level or basement rooms are generally of stronger construction than upper floors and subject to less vibration. If you plan to purchase an unusually large aquarium, and the foundation of your home is anything other than slab construction, it is prudent to first consult a structural engineer"
Seriously, I'd hate to think of what could happen in this case if the floor gives.
