If in doubt, culture your own - red wigglers are super easy.
Matt
Matt
MadRussian79;4827932; said:Just like any live food it's a question of source. Unless you necropsy the ray there is no way to tell what killed it. There are a couple of ways a live and apparently healthy earthworm can kill a raw. The first is embedded particulate on the worm, Small shards of glass or plastic adhered or partly penetrating the worm can do it. Though only inflicting a superficial scratch on the worm. Annelids will have a different poison tolerance than rays as well given that they evolved on different continents.
Both of these problems are avoided by using a reliable source. Same goes with any pet food.