The Alligator Snapping Turtle is the largest fresh water turtle in the world. They are capable of causing extreme injury to unwary owners when kept in captivity. During the week I assisted my Nephew Geoff in the relocation of his 40lb pet turtle. He is a competent, passionate owner who cares for his "pet" superbly. It eats a varied diet, including meats of all kinds as well as fresh fish. As you can see, it is a primitive, mighty beast with the ability to amputate fingers if! 

Have a look at this article on Wikipedia.   It would be totally wrong to keep anything like this in captivity unless you were able to look after it in a proper manner. They need space and a varied balanced diet. This one was re-homed by my nephew who knows how to provide the correct conditions.It lives a luxury lifestyle  with everything it requires to thrive. I am always interested to see how he is doing and have seen him grow up tothis monstrous size over the last few years.