They haven't been a bit aggressive thus far, but they're still very new in the tank. They aren't established yet. They're also in with several larger aggressive/semi-aggressive fish that can hold their own. I'm not envisioning any problems at the moment, but that may change if I add any other fish. I'm almost thinking I'm going to stop for now. I only have 8 fish in there, but there are 3 fish that will will get fairly large. And several of the fish are aggressive and territorial, so I'm treading a fairly fine line with the stocking limits. I'm really quite satisfied with what I have, goby notwithstanding. And after the addition of the maroon clowns (which haven't been harassed by anything in the tank, even the dwarf angel), I may not be able to safely add a peaceful fish like a goby. I think after this it's just going to be inverts and coral. Possibly a rock flower nem or maximini nem (or both!).