Actually, the first time I watched my cray eat a live fish I was rather disturbed.
You see, when she catches one she eats it, well, alive, then when she's had her full she lets it go, still alive and half eaten.
One, I felt sorry for the half a fish trying to swim, and two, I had to take it out and dipose of it so it wouldnt eventually soil the tank.
I've found that each time she catches one, I have to "give" it back to her, upon doing so she'll eat some more, but eventually I do have to take the rest out.
I also have to stir up her hiding spots during water changes to "find" parts she may of burried in the sand.
But, either way, she's cool to watch.