Some larger adults have been found to exhibit greatly enlarged jaw surfaces perhaps indicating a preference for mollusks. These guys are messy. They grow fairly quickly because they get most of the food in community settings. We have moved all of ours outside and they have flourished. Soft-shell turtles are very susceptible to shell rot and fungal infections on both plastron and carapace, especially in community settings indoors.
Minor scratches turn into life threatening infections.
If you buy a soft-shell turtle make sure its shell is flawless both top and bottom. Fighting the infections, once started, is very difficult and frustrating. Giving an injection to an unwilling soft-shell turtle redefines challenging. Prevention is the key here. We have found that sunshine, fresh air and space are the best preventatives.