just chop the shrimp to the width of your rays mouth size. that's should solve the problem from the chewing into bits and peices.. i don't agree on the massivore making a mess on your tank.. i feed that to my male ray also but when i turn the filter back on and wait an hour or so the water clears right up.. i'm running an eheim 2260 filter only for my 180 tank.. one 25" arowana, breeding pair of Marbles 15-17" , 2 datnoids 6-7", and 2 blood red parrots 4-5"..
wow I have a Fluval FX5 and Fluval 405 full of ceramic rings and can't seem to keep the water clear for more than two days. As far as the shrimp goes I cut it up really small they just chew it up and spit it out because they don't want it once they start to eat it I'm sure it won't be a problem.

