Musk turtles will eat anything they can catch, luckily they can't catch much of anything other than small earth worms and other small slow invertebrates. Of course a sick fish will be fair game but I keep mine with cardinal tetras, debawie cats, glass cats and other small fishes. Large fish will eat mud or musk turtles so be careful about big fishes. It's best to start with a baby musk turtle, about the size of a nickle or dime. An adult will not settle down to captivity as quickly as a baby will and an adult is more used to catching prey. A baby will get used to prepared food and ignore anything else (probably just lazy).