identification of potamotrygon motoro

[Ginger_newbie]

Hello
I was thinking about buying this ray, but i was curios to see if anyone could id the ray in the picture and tell me the adult size of it?
so I could see if my tank were big enough for
I have a 900 liters aquarium with the messuerments 200cmX75cmX60cm

 

[Stingraykeeper23]

Female motoro stingray