i've tried them before, and they don't really work.
if you are lucky, they hide for about a month, then you start to see a few aiptasia missing, and then a few nudis crawling around (more than you put in because they do breed in the tank). then all the aiptasia appear to be gone, and the nudis all starve to death. then you realize that rather than eat them all the way to the rock, they left aiptasia scraps all over the tank (and plenty in the overflow/plumbing/sump/..., and they all sprout back worse than before in no time. If they really did work well, they'd be a *whole* lot more common than they are, someone like ORA would be breeding them commercially.
you could catch them and spread them around to other people's tanks before they starve in yours, so that you could get some back once your aiptasia sprout back, but it's so much easier just to get a bunch of peppermints. A copperband is the best, but they can be touchy.
