First, anything that eats polyps is not 100% reef safe.
Second, any other significant fish load in the tank?
With those caveats in mind...
I had no luck with Filefish and due to their overall slow character I can't recommend them for most SPS tanks. Plus, which Filefish are we talking about? Leatherjacket? Orange-spot? Hard to say which will each which type of coral. (Plus they are butt-ugly!)
There's a Moorish Idol look-a-like Butterflyfish (whose name is escaping me) that also gets recommended for this function which I cannot personally recommend - known in my experience to favor clam mantle.
It's possible Peppermints could work, but for a tank that size, you'll need an army and I'm not sure it's cost effective. I would start with no less than 30. That's about $200 in peppermints here in my neck of the woods - and who wants that many in their tank when the mess is cleaned up? (I've been through this before, and I'm serious.) They won't eat 'em by preference either, so they'll have to exhaust the tank of other foods before they are even likely to get to the Majanos. In my experience, I've never seen Peppermints eat anything but Aiptasia anyway.
As someone above suggested, a long-nose Butterfly would be another option - but they aren't the most hearty. (not the least hearty either - that might be the Copperband - so if they make the owner's heart sing, give one or more a try)
My personal recommendation - what I've had the most luck with in the field - is Klein's Butterfly.
Klein's Butterflyfish is one of the heartiest, best-schooling (i.e. lacking aggression) fish you'll ever see - particularly among Butterflyfish. You could add one (solo) and expect some results, but due to the size of the tank and infestation and depending on the rest of the fish load, I'd try to start with 3-7 of them. They are very inexpensive - less than $40/each in my neck of the woods. In addition, of the two individual Kleins I've read about (never happened to one that I sold, and I maintained contact with the customer to whom I sold my very first one) that "went off the ranch" and ate non-pest polyps, they focused exclusively on Zoanthids.
Having said all that, I've also got to add: there is no bullet-proof solution. Everything you try may decide to ignore the Majanos. This is especially true if the tank is still being fed while they're supposed to be taking care of the Majanos. This is
double especially true if the tank is being overfed.
I recommend to withhold feedings if at all possible until they are seen to be eating Majanos.
Once the disaster is past, make sure the Kleins are well fed (as normal) and they should remain model citizens - even in the presence of Zoanthids. (With the corals you mentioned, I can't imagine a problem even down the road.)
-Matt
his wife who is trying to learn the ropes and keep his tank going in his memory asked me what to do... She said all I remember is him saying it was over ran with these pests.... That it is..
