That's why I wonder about getting a couple of Berghia. The aptasia are never in the same place. They are random all over the tank. I can't see the Berghia covering that much real estate. More would just starve.Not sure what to say. Berghia will have to find and to eat them, if the aiptasias are close to each other, probably putting the nudis near the aiptasia, they will find and eat them (and the area there). Someone say is getting 10 for 170 like I member, but not report back what's done there.
Really can't tell you which one will be 100% successful for you, I can say what I test already, like most of the methods I put in the main, work well for me, not all are that good, I only don't test ever the Filefish and the peppermint shrimp. 3 Berghia work very well for friend of mi having 150 tank, and he had to bread Aiptasia and put in the tank ;Woot ,to can keep the Berghia alive.
Good luck, you can try, 2 I don't think will be enough for 200, but if they catch them at the locations where you have aiptasia..., probably will be good point.