Well, I did fear the death of my American Eel once, but it survived. What happened was I was feeding the crabs and the eel with some frozen mackerel that I cut up. So I gave the eel all soft meat, but I gave one of the cabs a peice of meat with a vertabrae in it. So, being the theft that he is, he stole the crab's peice and had the vertabrae stuck in his throat for about 4 or 5 days. He kept opening his mouth wide and rolling, and everytime I could see the bone in his mouth. The eel was only about 9 or 10 inches, and the bone was about the size of a pencil earaser. Eventually he spit it out and I found the bone laying at the bottom of the tank, so I removed it.