125G is WAY too narrow. You ideally need a tank with something like a 4'x4' footprint. If you can't go custom you would at the very least need to find a tank 2' wide. But 2' in my opinion is cruel for an adult ray.
As said above, Blue Spots rarely live more than a few months to a year in captivity.
What about freshwater rays? They have much, much better success in aquariums and you can get some that stay relatively small. You would still need at least a 180G for most of them though because the 2' width is still necessary.