From what I have heard they are extremely prone to bacterial infections, and yes they get large and Im just the type of person who thinks that if something gets past a certain size its just not fair to keep it in captivity if you cant supply a large enough area. If a ray gets 12" not counting the tail I would think even a 200 gallon would be snug, but Ive never kept one so its beyond me. if im not mistaken Sammystingray had a blue spot, you might try and talk to him.