I would suggest doing a bunch of research before jumping in with both feet. Check out the stickies in the Stingray section....there is alot of good info there.
Rays need a minimum tank of 180 gallons (for life)
Rays are demanding of CLEAN water...0 ammonia, 0 Nitrite and 20 ppm or less of Nitrates. Great fish but you need to be prepared to do the extra water changes, buy the bigger tank, over filter, blow your budget on food.....
Good Luck!
Once you get a ray...ypu wont go back!