130 gallons is a lot heavier than the average person.
I beg to differ on this statement 130g tank weighs about 1300 pounds when not in motion when you walk by it it goes into motion. As far as being OK to have on main floor I would only put it where a bath tub would be or in a alcove as those areas are made to hold extra weight also the main supporting wall that runs the length of the house is mad to support extra weight. if you have the tank perpendicular to the floor joists they will hold more weights you are distributing the weight over more floor joists a 6 foot tank is over at least 4 floor joists. I would phone a engineering firm and ask to talk to someone about the situation you have. now if you can have the tank perpendicular to the joist and on top of where a wall is down stairs it would be OK then I would think.Or put it where the utility room is and have telescoping posts put in below the tank that should be goodI would think, but I am not a structural engineer.

Bill