Rays seem to have a high tolerance for bull****. At least mine seem to. I took away their sand because they and the oscars were feeding the fx6s mouthfuls of sand. They have since taken to "blowing" on each other and trying to kick flip my arowana, much to her annoyance. New antics include running up the side of the tank, and jumping onto the backs of larger fish, as well as shoveling each other off the ground.That's pretty trippy and she seems to be okay with it or she would have stung him by now I would think
In my experience, pearl rays (captive or wild) and wild caught rays are most likely to sting, although the chances of this depend greatly on the individual. As long as your ray isn't stressed for trying to get away, it is likely curious behavior that will pass. If not, you will be the proud parent of something akin to if Ms. Piggy and Kermit had a kid.
Best of luck with your "needy" arowana ?