Severums aren't as nasty but they will still pick at stuff. Being that inverts are incredibly vulnerable when they shed it would be tough. It's a catch 22 here because if you get a prawn that is bigger than the cichlid, it could easily take that thing down. But there is also that slight chance the fish would get it when it sheds. Lots of hiding places is the best policy. Good luck finding a prawn if you go that route.