once day with a turkey baster for worms. i make sur they both get a few god squirts, then i squirt some around the rocks and fake plants so they can hunt for awhile, but not have any left over by nights end.
theres also a constant supply of glass shrimp in there for them. i go through about 100 ghosts every 2-3 weeks.
never stop ! my rays will eat as much as I will give them. But I dont like doing daily water changes so feed them as much as they can eat in an hour, then u will know how much food to put in the tank.
It depends on the size/age of the ray. For youngsters I feed 2-4x/day for the first year. Once they are adult size for most I feed 3x/week but they are fed to satiation.