MAN O MAN!!! i should have kept reading before i posted that last response. sorry you lost the little guy. i would set-up a quarintine tank before you try the next time. they like to "chill the most" for a couple weeks before they are ready for tank mates. but thats just my opinion
try keeping the lights on all day and night. put the recommended dosage of Lugols iodine in the tank. (that will help with any infections) then put a good amount of live blackworms in. i got all my stingrays to eat this way but i also had them in a quarintine tank by themselves until they were eating well. Hope this helps.