Are you referring to the motoro in the picture thread that you just posted. If you are, here are a couple things to consider. First, when referring to a rays size most people measure the size of the disk not head to tail. So, your 10" head to tail motoro is actually 5". This will help you get more accurate responses. Yes, a 5" motoro will go fine with your dat. Second, a 5" motoro needs to eat everyday or twice a day. Feeding every other day is probably not going to be enough.
Lastly, if you are referring to a different ray than in your picture thread just disregard everything I just said