It all depends on the foot print, a lot of big tanks tend to just be tall with no extra depth.
You know these are freshwater stingrays right ?
I do understand that the tank is freshwater but salt stingrays are in similar size or at least the stingray i plan to get. And my tank is being custom made and the tank is 32 inches wide almost 3 feet. and it's 6 feet long would that size be good enough for a stingray and btw the back wall will be covered with rock
The tank is being made and when it arrives i'll post pics of it and then post pics of it when it has rocks to show you the size of it.
Just how much research exactly have you done on SW stingrays? Which ray are you looking at getting?
The most common one (the Blue Spotted Ribbontail) has a very poor history in aquaria with only one in 10 living more thana year in captivity (and yes, that figure includes public aquaria trying to keep them as well). As a result of this one really has to look into other rays, but therein one comes across dietry problems as a number of rays eat worms and such from the sand, so getting them onto prepared food, or even live shrimp becomes a task.
If you really are serious about wanting a SW stingray then your best starting point will be to buy Aquarium Sharks and Rays by Scott W. Michael. Some of the sizes he gives are a little small, but he does give very good info on setting up a tank for Elasmobranches and on how to look after them.