I would strongly recomend employing a structural engineer to advise on whether the floor can take the weight before placing such a large tank on an upstairs floor, our downstairs floor sagged noticably when we filled up the 150 gallon tank in our frontroom, i certainly wouldnt feel comfortable placing any of my larger tanks in there.
If you can find them then a pair or trio of scobina would be ok for a tank that size, tankmates would need to be kept to a minimum though to keep the water parameters within safe levels for rays so avoid large fish that need to be kept in schools.
If you can find them then a pair or trio of scobina would be ok for a tank that size, tankmates would need to be kept to a minimum though to keep the water parameters within safe levels for rays so avoid large fish that need to be kept in schools.