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.
Wounds seem to heal themselves outdoors.
I have seen soft-shell turtles continue to kill fish long after they have stopped eating, and just let the dead fish rot. The other remedy for soft-shell disagreements is enough space for the less dominant ones to escape. I worried that the concrete ponds would scratch their plastrons and that other turtle claws would scratch their carapaces. They also appear to lift themselves up slightly before they launch themselves into the pond when frightened. Our adult smooth soft shells have mated and laid in our yard the last two years.