they shouldn't, I have at least one pistol shrimp (possibly more) that's been in there since day one. And I've had 3 peppermints in there for a little while now and no issues at all. Besides, the shrimp/goby will rarely, if ever leave their little cave that they make. Also, make sure you do your research because not all gobies will pair with a pistol shrimp. And on top of that, occasionally they will only pair with a certain type of pistol.