I've tried them all.. nudi's, file fish, copperband, aiptasia x. I bought 5 nudi's for my tank and after getting them acclimated they went to work on the aiptasia then about 3 days later they were gone, out of sight, my wrasses thought they were bite size morsels and ate them. Later, I bought 2 file fish to mow down the aiptasia, they both died after about 2 weeks in the tank, I think that they were bullied by my wrasses or tangs (I never witnessed them eat aiptasia). I even spent the money for a Burgess butterflyfish, this guy ate aiptasia like crazy, but because they are hard to keep in captivity he only lasted a week in my tank. I then bought 2 copperbands and one survived but doesn't lay a finger on the aiptasia, I've had the copperband for about 5-6 months now and all he does is graze on copepods all day and wait for the meaty frozen food to be delivered at dinner time.
In the mean time, aiptasia got so bad that people started joking that I was farming the pest, haha we joked about it but the last straw came when they started to sting and kill the coral, it was then I resorted to aiptasia X. I spent probably 2 hours with my hands in the tank feeding this delightful poison to the pesky buggers. I went through 1 1/2 bottles that time and after about 2 weeks later I went back in and got the rest of the ones I could reach. Now, my tank is virtually free of them they pop up every now and then but when they make the mistake of staking claim on an easy to get to rock, I lay waste to them in seconds.
Although I was a skeptic of the aiptaisa x it's the only for sure method of getting rid of them. You can buy fish, inverts and hope they eat aiptasia and also survive long term, but that's all hit and miss. Because I bought so many bottles of aiptasia x, I was able to take the "needles" and connect them all together with an empty ink pen tube so that I have a longer reach, now I can weasel may way into those hard to reach crevices inside the rock work.