Well, pretty much anything will attack fry (the parents eat them most of the time) That is a reason to watch out for them though or to say that they are aggressive. With adult fish they wount cause a problem. I have had ghost shrimp for a while and I have witnessed fish taking food right out of their poor defenseless little hands and the shrimp do nothing about it, because they can't. If you put them in a semi-aggressive tank they probably wouldn't make it for long.