Peppermint shrimp have been known to eat the really small ones, but it's really a hit or miss with those guys. Berghia nudibranches also eat them, but they need tons of aiptasia to consume otherwise they will perish, so that's hardly a worthy option. Trust me, the Aiptasia X will work for you better then any creature could in this situation.
Also, just a word of advice, when it comes to aiptasia, chances are if there's one, there's more somewhere in spots you can not see/reach. I'm not saying this is always the case, I'm just saying be wary, and keep an eye out for more.