They eat big fish. If it hangs out it is a compliment to your fish raising skills. Of course it is eating all of your fish raising skills. They do clean dead fish up for you but so do minnows and turtles without taking any live ones. They are very easy to clean and are excellent table fair when prepared along the lines of frog legs. Much, Much better than turtle. Tons of clean white meat in legs and tail.
Toby