Ive bought 2 from Elite, not one ever ate a single aptasia, not sure who their supplier is for them, but they are not coming out of the right part of the ocean to eat aptasia, I had good success with one I got from Aquamart (1 of the 2), and I had Nick w/ Ambrosia Aquatics special order me one. The one i got form Nick began eating aptasia almost as soon as I added him to the DT.
just keep in mind that as with any fish thay may or may not do the job