well it is a well established tank and the nitrates were around 20ppm. i forget the other paremeters but they were the same as they've been for the past year. i am well aware of the sensitivity of young retics because I had lost my first one after two weeks. i spent $200 renovating the tank after that to make sure the new stingray had the right substrate, ph, hardness, and tankmates. the tankmates didnt bother him and i didnt have "active" fish to spook him as he rarely dug into the sand. and no the sand was not silica, it was ecocomplete and perfect for the needs of stingrays. my only thoughts are that it is a baby retic. and they are doomed to begin with... but that's alot of time effort and money, not to mention the coolest fish i ever had, down the drain....
the ray was about 5" across. he was very healthy.
and no more walls will be assaulted. i've learned my lesson. (but if those walls talk smack again i am goin at it with the sledgehammer like you said)