IME, I have not encountered any eel related fish/invert deaths in my tanks. But that does not mean that this scenario will not happen to you. SFE love to dig so the rocks cannot be stacked too high or in precarious positions. My zebra is abit more easier and his tank consists of a T shaped PVC
pipe that he inhabits most of the time and the rocks are stacked and has not been knocked over yet. Both eels are great, and in most part very docile.