I've done my research I know what I'm getting into and been studying them for over a year a hystrix sting ray and retic would be the smaller of them and while they are not the hardiest but for a 210 gallon tank they would be the best fit. I don't want to buy a stingray that is going to be three feet wide like a motoro ray. I also think I would be fine with a stingray less hardy I have had my fair share of having fish that are difficult to keep. Then on top of that my lfs will order them for me but I have to wait until summer which isn't that bad. aThey are only going to charge me $40 for it also. So I figure I have spent more money of fish that might not live if I miss one little step in acclimation or general care. Not to sound like I don't care about the fish, which is not true, Forty dollars compared to a couple hundred for an even bigger tank isn't something I want to do right now. Eventually when I settle down and have enough space i', going to have an indoor pond that would be big enough for a black ray or a motoro just i can't feasibly have that now.