For aptasia you have several options...

-Peppermint Shrimp
-Copperband Butterfly
-Manual removal, i.e. Joe's Juice, Kalk, Lemon Juice
-Berghia Nudibranch

Aptasia grow readily in light, without light, with food sources, without food source. They are one of a reefers worst nightmare and WE ALL HAVE THEM, lol!

Personally, I use a syringe and kalk and target them one by one. It can take some time but I feel this is the best method, JMO. I also have a peppermint shrimp but I'm not sure that he is eating any aptasia.

Christopher