I wouldn't say they are too young - my maroon was just a youngin' when he hosted the GBTA. If the bucket technique didn't work, I'd suggest just giving them some time. I think mine hosted so fast because of the other fish that were in the tank - they got nipped at every once in a while. The nem provided a safety house for them.
That's cool that the clowns hosted the xenia. Now that my nem has died, I'd love to see the clowns in my tank host something (because now adays, apparently they'll host anything!). Be neat to see!
