there are only a blue dot stingray a.k.a bluespotted ribbontail ray(taeniura lymma), which is impossible to keep in captivity for more than a year and should be left in the ocean for just that reason OR the bluspotted stingray(dasyatis kuhlii)whiihc is a great aquarium ray but impossible to find in the aquarium trade.
rays do well in small tanks but they dont thrive.. we as humans can live in a closet if well fed but it doesnt mean we would be happy , you def. can keep a smaller ray in a 180, but not a corner 180 since as i said it just doesnt give him enough room to swim around.....
HOWEVER you can get a baby ray and let him grow up in there and you might be able to get away with it as long as you would be willing to upgrade..i can imagine my two stingrays in your tanks just becasue they wouldnt have room to swim back andd fourth liek they love to do..and they also need ALOT of room to bury themselves...
im in no way saying you DEF. cant have a ray as stated you can do a baby yellow, or cortez or cali but in the future would need to upgrade...
i hope i somewhat helped and didnt sound lieke i was mean or trying ot turn you away from rays because they are VERY rewarding animals to keep!