So is there a stingray species out there that can live long term in a 220g tank? Marble or hystrix is what I'm thinking but need first hand advice of those who have kept either.
It depends on the footprint of the tank. I haven't kept either of those species, but I have a P. Signata (similar size) that's currently about 15 inches in a 210 half cylinder that's 72x36x24 and it's totally fine.