If the 70 x 40 tank is for the robo,that would be a very good size
However the size generally is pretty small for Syrians,so if you'd use that size for a Syrian you'd need to pay close attention and watch for any obsessive behaviors(leaping at the sides,obsessive corner digging and chewing,etc)and be prepared to upgrade if those show regardless of cage size if they don't go away permanently with setup changes.